各装置の規格が分かっていないのでコメントのしようがないのですが。Ｗｉｎｄｏｗｓで試してみました?　たぶんＷｉｎｄｏｗｓでも表示されないのでは?
『unknown EDID version 0』からすると、ディスプレイの規格データが読めないといっているので、現状の２アダプタからⅠアダプタに変更するよりしかたがないのではないでしょうか。通常はディスプレイには入力端子が2つ以上付いていると思いますので、ディスプレイコードをもう1本用意して、直接Netwalker→USBディスプレイ出力機に接続して手動で切り替えるか、別のディスプレイを用意するかだと思います。

MS-Windowsの場合、機器から情報が取れなくても、とりあえずがんがんと動きます。リスクがあっても間違えている可能性があっても動くように設定されているものが多いです(無線LANルータの設定とか、怖いものがありますね・・・)
Ubuntsuの今のバージョン付近の場合、機器から情報が取れない場合(切り替え機等で情報が欠落してしまうケースや、そもそも未対応の機器の場合とか)は、手動で正しく定義しないと動かないようです。機器に対応した、メーカーから提供される専用のドライバがないためになおさら　ということになります。

そこで、設定内容そのものは掲載いただいているのですが、その設定内容が読み込まれて起動されるときに、内部でどんなエラーが出ているのかが分からないと、ファイルとにらめっこして間違いを探すのは結構大変です。
# 特に、特殊な環境でほかにそっくり同じ環境の人が少なさそうな場合。私自身は、netwalkerについても、USB-ディスプレイについても、ほぼわかりません。
もし、/var/log/Xorg.0.log が作成されているようであれば、その中に、なにかエラー(「(EE)」を含む行)が出ていたりしないでしょうか？そこまで動いてないとすると・・・ /var/log/syslog か、 /var/log/messages にいずれかあたりに、なにか情報があればよいのですが・・・

weykさん、Crushさんコメントありがとうございます。

デフォルト解像度でもいいので表示できればありがたいのですが、
netwalkerの動き的には、xwindowが起動できないので、ディスプレイにも表示されないと勝手に解釈しているのですが、
Crushさんのおっしゃるとおり、切り替え機が無ければ、displaylink系のUSB出力機でもxwindowが起動して表示できるので、
エラーをスルーさせるとか、とにかくxwindowが起動できれば、ディスプレイに出るのだと希望を持ってます。

weykさんのXorg.0.logの件ですが以下となります。
---------------------------------
X.Org X Server 1.6.0
Release Date: 2009-2-25
X Protocol Version 11, Revision 0
Build Operating System: Linux 2.6.30versatile1 armv7l Ubuntu
Current Operating System: Linux ubuntu 2.6.28-15-araneo #50fsl1araneo19-Ubuntu PREEMPT Mon Jan 25 15:54:27 UTC 2010 armv7l
Build Date: 13 July 2009  08:06:39PM
xorg-server 2:1.6.0-0ubuntu16netbook3 (buildd@)
    Before reporting problems, check http://wiki.x.org
    to make sure that you have the latest version.
Markers: (--) probed, (**) from config file, (==) default setting,
    (++) from command line, (!!) notice, (II) informational,
    (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
(==) Log file: "/var/log/Xorg.0.log", Time: Tue Jun 29 21:09:49 2010
(==) Using config file: "/etc/X11/xorg.conf"
(==) ServerLayout "Default Layout"
(**) |-->Screen "Default Screen" (0)
(**) |   |-->Monitor "Configured Monitor"
(**) |   |-->Device "Configured Video Device"
(**) |-->Screen "Screen[DLUSBVGA]" (1)
(**) |   |-->Monitor "Monitor[DLUSBVGA]"
(**) |   |-->Device "Device[DLUSBVGA]"
(**) |-->Input Device "Generic Keyboard"
(**) |-->Input Device "Configured Mouse"
(**) Option "DontZap" "False"
(==) Automatically adding devices
(==) Automatically enabling devices
(WW) The directory "/usr/share/fonts/X11/cyrillic" does not exist.
    Entry deleted from font path.
(==) FontPath set to:
    /usr/share/fonts/X11/misc,
    /usr/share/fonts/X11/100dpi/:unscaled,
    /usr/share/fonts/X11/75dpi/:unscaled,
    /usr/share/fonts/X11/Type1,
    /usr/share/fonts/X11/100dpi,
    /usr/share/fonts/X11/75dpi,
    /var/lib/defoma/x-ttcidfont-conf.d/dirs/TrueType,
    built-ins
(**) ModulePath set to "/usr/lib/xorg/modules,/usr/local/lib/xorg/modules"
(WW) AllowEmptyInput is on, devices using drivers 'kbd', 'mouse' or 'vmmouse' will be disabled.
(WW) Disabling Generic Keyboard
(WW) Disabling Configured Mouse
(II) Loader magic: 0xd90
(II) Module ABI versions:
    X.Org ANSI C Emulation: 0.4
    X.Org Video Driver: 5.0
    X.Org XInput driver : 4.0
    X.Org Server Extension : 2.0
(II) Loader running on linux
(--) using VT number 7

(II) Open APM successful
(II) System resource ranges:
(II) LoadModule: "extmod"
(II) Loading /usr/lib/xorg/modules/extensions//libextmod.so
(II) Module extmod: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    Module class: X.Org Server Extension
    ABI class: X.Org Server Extension, version 2.0
(II) Loading extension MIT-SCREEN-SAVER
(II) Loading extension XFree86-VidModeExtension
(II) Loading extension XFree86-DGA
(II) Loading extension DPMS
(II) Loading extension XVideo
(II) Loading extension XVideo-MotionCompensation
(II) Loading extension X-Resource
(II) LoadModule: "dbe"
(II) Loading /usr/lib/xorg/modules/extensions//libdbe.so
(II) Module dbe: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    Module class: X.Org Server Extension
    ABI class: X.Org Server Extension, version 2.0
(II) Loading extension DOUBLE-BUFFER
(II) LoadModule: "glx"
(II) Loading /usr/lib/xorg/modules/extensions//libglx.so
(II) Module glx: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    ABI class: X.Org Server Extension, version 2.0
(==) AIGLX enabled
(II) Loading extension GLX
(II) LoadModule: "record"
(II) Loading /usr/lib/xorg/modules/extensions//librecord.so
(II) Module record: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.13.0
    Module class: X.Org Server Extension
    ABI class: X.Org Server Extension, version 2.0
(II) Loading extension RECORD
(II) LoadModule: "dri"
(II) Loading /usr/lib/xorg/modules/extensions//libdri.so
(II) Module dri: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    ABI class: X.Org Server Extension, version 2.0
(II) Loading extension XFree86-DRI
(II) LoadModule: "dri2"
(II) Loading /usr/lib/xorg/modules/extensions//libdri2.so
(II) Module dri2: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    ABI class: X.Org Server Extension, version 2.0
(II) Loading extension DRI2
Primary device is not PCI
(==) Matched fbdev for the autoconfigured driver
(==) Assigned the driver to the xf86ConfigLayout
(II) LoadModule: "fbdev"
(II) Loading /usr/lib/xorg/modules/drivers//fbdev_drv.so
(II) Module fbdev: vendor="X.Org Foundation"
    compiled for 1.5.99.902, module version = 0.4.0
    ABI class: X.Org Video Driver, version 5.0
(II) LoadModule: "displaylink"
(II) Loading /usr/local/lib/xorg/modules/drivers//displaylink_drv.so
(II) Module displaylink: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 0.0.1
    ABI class: X.Org Video Driver, version 5.0
(II) FBDEV: driver for framebuffer: fbdev
(II) DL: driver for : displaylink
(WW) Falling back to old probe method for fbdev
(II) Loading sub module "fbdevhw"
(II) LoadModule: "fbdevhw"
(II) Loading /usr/lib/xorg/modules/linux//libfbdevhw.so
(II) Module fbdevhw: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 0.0.2
    ABI class: X.Org Video Driver, version 5.0
(II) FBDEV(0): using default device
(WW) Falling back to old probe method for displaylink
(II) Loading sub module "fbdevhw"
(II) LoadModule: "fbdevhw"
(II) Reloading /usr/lib/xorg/modules/linux//libfbdevhw.so
(EE) open /dev/fb2: No such file or directory
(II) resource ranges after probing:
(II) FBDEV(0): Creating default Display subsection in Screen section
    "Default Screen" for depth/fbbpp 16/16
(==) FBDEV(0): Depth 16, (==) framebuffer bpp 16
(==) FBDEV(0): RGB weight 565
(==) FBDEV(0): Default visual is TrueColor
(==) FBDEV(0): Using gamma correction (1.0, 1.0, 1.0)
(II) FBDEV(0): hardware: DISP3 BG (video memory: 2400kB)
(II) FBDEV(0): checking modes against framebuffer device...
(II) FBDEV(0): checking modes against monitor...
(--) FBDEV(0): Virtual size is 1024x600 (pitch 1024)
(**) FBDEV(0):  Built-in mode "current": 33.2 MHz, 31.0 kHz, 51.0 Hz
(II) FBDEV(0): Modeline "current"x0.0   33.25  1024 1044 1052 1072  600 602 606 608 -hsync -vsync -csync (31.0 kHz)
(==) FBDEV(0): DPI set to (96, 96)
(II) Loading sub module "fb"
(II) LoadModule: "fb"
(II) Loading /usr/lib/xorg/modules//libfb.so
(II) Module fb: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.0.0
    ABI class: X.Org ANSI C Emulation, version 0.4
(**) FBDEV(0): using shadow framebuffer
(II) Loading sub module "shadow"
(II) LoadModule: "shadow"
(II) Loading /usr/lib/xorg/modules//libshadow.so
(II) Module shadow: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 1.1.0
    ABI class: X.Org ANSI C Emulation, version 0.4
(II) UnloadModule: "displaylink"
(II) Unloading /usr/local/lib/xorg/modules/drivers//displaylink_drv.so
(II) UnloadModule: "fbdevhw"
(II) do I need RAC?  No, I don't.
(II) resource ranges after preInit:
(==) FBDEV(0): Backing store disabled
(II) FBDEV(0): DPMS enabled
(==) RandR enabled
(II) Initializing built-in extension Generic Event Extension
(II) Initializing built-in extension SHAPE
(II) Initializing built-in extension MIT-SHM
(II) Initializing built-in extension XInputExtension
(II) Initializing built-in extension XTEST
(II) Initializing built-in extension BIG-REQUESTS
(II) Initializing built-in extension SYNC
(II) Initializing built-in extension XKEYBOARD
(II) Initializing built-in extension XC-MISC
(II) Initializing built-in extension SECURITY
(II) Initializing built-in extension XINERAMA
(II) Initializing built-in extension XFIXES
(II) Initializing built-in extension RENDER
(II) Initializing built-in extension RANDR
(II) Initializing built-in extension COMPOSITE
(II) Initializing built-in extension DAMAGE
(II) AIGLX: Screen 0 is not DRI2 capable
(II) AIGLX: Screen 0 is not DRI capable
(II) AIGLX: Loaded and initialized /usr/lib/dri/swrast_dri.so
(II) GLX: Initialized DRISWRAST GL provider for screen 0
(II) config/hal: Adding input device ATEN Advance Tech Inc. CS62USV1.0.071
(II) LoadModule: "evdev"
(II) Loading /usr/lib/xorg/modules/input//evdev_drv.so
(II) Module evdev: vendor="X.Org Foundation"
    compiled for 1.6.0, module version = 2.1.1
    Module class: X.Org XInput Driver
    ABI class: X.Org XInput driver, version 4.0
(**) ATEN Advance Tech Inc. CS62USV1.0.071: always reports core events
(**) ATEN Advance Tech Inc. CS62USV1.0.071: Device: "/dev/input/event7"
(II) ATEN Advance Tech Inc. CS62USV1.0.071: Found keys
(II) ATEN Advance Tech Inc. CS62USV1.0.071: Configuring as keyboard
(II) XINPUT: Adding extended input device "ATEN Advance Tech Inc. CS62USV1.0.071" (type: KEYBOARD)
(**) Option "xkb_rules" "evdev"
(**) ATEN Advance Tech Inc. CS62USV1.0.071: xkb_rules: "evdev"
(**) Option "xkb_model" "jp106"
(**) ATEN Advance Tech Inc. CS62USV1.0.071: xkb_model: "jp106"
(**) Option "xkb_layout" "jp,jp"
(**) ATEN Advance Tech Inc. CS62USV1.0.071: xkb_layout: "jp,jp"
(**) Option "xkb_variant" "106,"
(**) ATEN Advance Tech Inc. CS62USV1.0.071: xkb_variant: "106,"
(**) Option "xkb_options" "grp_led:scroll"
(**) ATEN Advance Tech Inc. CS62USV1.0.071: xkb_options: "grp_led:scroll"
(II) config/hal: Adding input device SHARP USB Keyboard
(**) SHARP USB Keyboard: always reports core events
(**) SHARP USB Keyboard: Device: "/dev/input/event5"
(II) SHARP USB Keyboard: Found keys
(II) SHARP USB Keyboard: Configuring as keyboard
(II) XINPUT: Adding extended input device "SHARP USB Keyboard" (type: KEYBOARD)
(**) Option "xkb_rules" "evdev"
(**) SHARP USB Keyboard: xkb_rules: "evdev"
(**) Option "xkb_model" "jp106"
(**) SHARP USB Keyboard: xkb_model: "jp106"
(**) Option "xkb_layout" "jp,jp"
(**) SHARP USB Keyboard: xkb_layout: "jp,jp"
(**) Option "xkb_variant" "106,"
(**) SHARP USB Keyboard: xkb_variant: "106,"
(**) Option "xkb_options" "grp_led:scroll"
(**) SHARP USB Keyboard: xkb_options: "grp_led:scroll"
(II) config/hal: Adding input device SHARP USB Keyboard
(**) SHARP USB Keyboard: always reports core events
(**) SHARP USB Keyboard: Device: "/dev/input/event6"
(II) SHARP USB Keyboard: Found keys
(II) SHARP USB Keyboard: Configuring as keyboard
(II) XINPUT: Adding extended input device "SHARP USB Keyboard" (type: KEYBOARD)
(**) Option "xkb_rules" "evdev"
(**) SHARP USB Keyboard: xkb_rules: "evdev"
(**) Option "xkb_model" "jp106"
(**) SHARP USB Keyboard: xkb_model: "jp106"
(**) Option "xkb_layout" "jp,jp"
(**) SHARP USB Keyboard: xkb_layout: "jp,jp"
(**) Option "xkb_variant" "106,"
(**) SHARP USB Keyboard: xkb_variant: "106,"
(**) Option "xkb_options" "grp_led:scroll"
(**) SHARP USB Keyboard: xkb_options: "grp_led:scroll"
(II) config/hal: Adding input device mxc_etk
(**) mxc_etk: always reports core events
(**) mxc_etk: Device: "/dev/input/event0"
(II) mxc_etk: Found keys
(II) mxc_etk: Configuring as keyboard
(II) XINPUT: Adding extended input device "mxc_etk" (type: KEYBOARD)
(**) Option "xkb_rules" "evdev"
(**) mxc_etk: xkb_rules: "evdev"
(**) Option "xkb_model" "jp106"
(**) mxc_etk: xkb_model: "jp106"
(**) Option "xkb_layout" "jp,jp"
(**) mxc_etk: xkb_layout: "jp,jp"
(**) Option "xkb_variant" "106,"
(**) mxc_etk: xkb_variant: "106,"
(**) Option "xkb_options" "grp_led:scroll"
(**) mxc_etk: xkb_options: "grp_led:scroll"
(II) config/hal: Adding input device ATEN Advance Tech Inc. CS62USV1.0.071
(**) ATEN Advance Tech Inc. CS62USV1.0.071: always reports core events
(**) ATEN Advance Tech Inc. CS62USV1.0.071: Device: "/dev/input/event8"
(II) ATEN Advance Tech Inc. CS62USV1.0.071: Found 5 mouse buttons
(II) ATEN Advance Tech Inc. CS62USV1.0.071: Found x and y relative axes
(II) ATEN Advance Tech Inc. CS62USV1.0.071: Configuring as mouse
(**) ATEN Advance Tech Inc. CS62USV1.0.071: YAxisMapping: buttons 4 and 5
(**) ATEN Advance Tech Inc. CS62USV1.0.071: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
(II) XINPUT: Adding extended input device "ATEN Advance Tech Inc. CS62USV1.0.071" (type: MOUSE)
(**) ATEN Advance Tech Inc. CS62USV1.0.071: (accel) keeping acceleration scheme 1
(**) ATEN Advance Tech Inc. CS62USV1.0.071: (accel) filter chain progression: 2.00
(**) ATEN Advance Tech Inc. CS62USV1.0.071: (accel) filter stage 0: 20.00 ms
(**) ATEN Advance Tech Inc. CS62USV1.0.071: (accel) set acceleration profile 0
(II) config/hal: Adding input device oj6sh
(**) oj6sh: always reports core events
(**) oj6sh: Device: "/dev/input/event1"
(II) oj6sh: Found 2 mouse buttons
(II) oj6sh: Found x and y relative axes
(II) oj6sh: Configuring as mouse
(**) oj6sh: YAxisMapping: buttons 4 and 5
(**) oj6sh: EmulateWheelButton: 4, EmulateWheelInertia: 10, EmulateWheelTimeout: 200
(II) XINPUT: Adding extended input device "oj6sh" (type: MOUSE)
(**) oj6sh: (accel) keeping acceleration scheme 1
(**) oj6sh: (accel) filter chain progression: 2.00
(**) oj6sh: (accel) filter stage 0: 20.00 ms
(**) oj6sh: (accel) set acceleration profile 0
(II) config/hal: Adding input device mxc_ts
(II) LoadModule: "evtouch"
(II) Loading /usr/lib/xorg/modules/input//evtouch_drv.so
(II) Module evtouch: vendor="Kenan Esau"
    compiled for 1.6.0, module version = 0.8.8
    Module class: X.Org XInput Driver
    ABI class: X.Org XInput driver, version 4.0
State: S_UNTOUCHED    Action: No Action        Button: 0
State: S_TOUCHED    Action: No Action        Button: 0
State: S_LONGTOUCHED    Action: down        Button: 1
State: S_MOVING    Action: No Action        Button: 0
State: S_MAYBETAPPED    Action: click        Button: 1
State: S_ONEANDAHALFTAP    Action: down        Button: 3
(**) Option "MinX" "32"
(**) Option "MaxX" "1000"
(**) Option "MinY" "10"
(**) Option "MaxY" "578"
(**) Option "x0" "14"
(**) Option "y0" "8"
(**) Option "x1" "-8"
(**) Option "y1" "2"
(**) Option "x2" "-15"
(**) Option "y2" "2"
(**) Option "x3" "11"
(**) Option "y3" "-8"
(**) Option "x4" "-2"
(**) Option "y4" "-2"
(**) Option "x5" "-1"
(**) Option "y5" "15"
(**) Option "x6" "11"
(**) Option "y6" "-9"
(**) Option "x7" "7"
(**) Option "y7" "-12"
(**) Option "x8" "0"
(**) Option "y8" "-11"
(**) EVTouch TouchScreen: always reports core events
(II) XINPUT: Adding extended input device "EVTouch TouchScreen" (type: TOUCHSCREEN)
(**) EVTouch TouchScreen: (accel) keeping acceleration scheme 1
(**) EVTouch TouchScreen: (accel) filter chain progression: 2.00
(**) EVTouch TouchScreen: (accel) filter stage 0: 20.00 ms
(**) EVTouch TouchScreen: (accel) set acceleration profile 0
(**) Option "Device" "/dev/input/event4"
---------------------------------------

CrushさんのサンワのFAQですが、低い解像度がでるなら、まだましです。私のはディスプレイに表示すらできません。
また、切替機の改造はすごいとしか言い様がありませんが、デフォルト解像度でも表示できるだけましなので対応する切替機に代える手もありますが、
SW-KVM2UUの切替機の特徴は、キーボードのコントロールを2回押すと切り替えられるのが、私にとってメリットです。

weykさんからご指摘頂きました、
Option "DevicePresence" "true"をfalseに変えてもだめでした。
また、以下のxorg.confは、displaylinkで出力する際の初期パターンなのですが、Option "DevicePresence"の指定はありません。
この初期パターンが駄目なのでいろいろ記述を加えたりしております。

#### xorg.conf for netwalker with dislaylink
Section "Files"
ModulePath "/usr/lib/xorg/modules"
ModulePath "/usr/local/lib/xorg/modules"
EndSection

Section "Device"
Identifier "Configured Video Device"
EndSection

Section "Monitor"
Identifier "Configured Monitor"
EndSection

Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
EndSection

Section "ServerFlags"
Option "DontZap" "False"
EndSection

### for USB-VGA ###

Section "Device"
Identifier "Device[DLUSBVGA]"
VendorName "Device Vendor"
BoardName "Device Vendor"
Driver "displaylink"
Option "fbdev" "/dev/fb2"
EndSection

Section "Monitor"
Identifier "Monitor[DLUSBVGA]"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
VertRefresh 50-76
HorizSync 30-90
EndSection


Section "Screen"
Identifier "Screen[DLUSBVGA]"
Device "Device[DLUSBVGA]"
Monitor "Monitor[DLUSBVGA]"
DefaultDepth 16
SubSection "Display"
  Depth 16
  Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
  Depth 8
  Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
SubSection "Display"
  Depth 24
  Modes "1280x1024" "1024x768" "800x600" "640x480"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Default Screen"
Screen 1 "Screen[DLUSBVGA]" RightOf "Default Screen"
EndSection

#### end of xorg.conf