これをみつけたので貼り付けてみました
# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by dexconf, the Debian X Configuration tool, using
# values from the debconf database.
#
# Edit this file with caution, and see the xorg.conf manual page.
# (Type “man xorg.conf” at the shell prompt.)
#
# This file is automatically updated on xserver-xorg package upgrades *only*
# if it has not been modified since the last upgrade of the xserver-xorg
# package.
#
# Note that some configuration settings that could be done previously
# in this file, now are automatically configured by the server and settings
# here are ignored.
#
# If you have edited this file but would like it to be automatically updated
# again, run the following command:
#   sudo dpkg-reconfigure -phigh xserver-xorg

Section “Device”
Identifier    ”Configured Video Device”
EndSection

Section “Monitor”
Identifier    ”Configured Monitor”
HorizSync      31.5-81.1
VertRefresh    56.0-76.0
EndSection

Section “Screen”
Identifier    ”Default Screen”
Monitor        ”Configured Monitor”
Device        ”Configured Video Device”
DefaultDepth    24

SubSection “Display”
Viewport    0 0
Depth 24
Modes “1280×1024″
EndSubSection
EndSection

しかしこれに戻ります。
# xorg.conf (X.Org X Window System server configuration file)
#
# This file was generated by failsafeDexconf, using
# values from the debconf database and some overrides to use vesa mode.
#
# You should use dexconf or another such tool for creating a "real" xorg.conf
# For example:
#   sudo dpkg-reconfigure -phigh xserver-xorg
Section "InputDevice"
    Identifier    "Generic Keyboard"
    Driver        "kbd"
    Option        "XkbRules"    "xorg"
    Option        "XkbModel"    "jp106"
    Option        "XkbLayout"    "jp"
    Option        "XkbOptions"    "lv3:ralt_switch"
EndSection

Section "InputDevice"
    Identifier    "Configured Mouse"
    Driver        "mouse"
EndSection


Section "InputDevice"
    Identifier    "Synaptics Touchpad"
    Driver        "synaptics"
    Option        "SendCoreEvents"    "true"
    Option        "Device"    "/dev/psaux"
    Option        "Protocol"    "auto-dev"
    Option        "HorizEdgeScroll"    "0"
EndSection
Section "Device"
    Identifier    "Configured Video Device"
    Boardname    "vesa"
    Busid        "PCI:1:5:0"
    Driver        "vesa"
    Screen    0
EndSection

Section "Monitor"
    Identifier    "Configured Monitor"
    Vendorname    "Plug 'n' Play"
    Modelname    "Plug 'n' Play"
  modeline  "640x480@60" 25.2 640 656 752 800 480 490 492 525 -vsync -hsync
    Gamma    1.0
EndSection

Section "Screen"
    Identifier    "Default Screen"
    Device        "Configured Video Device"
    Monitor        "Configured Monitor"
    Defaultdepth    24
    SubSection "Display"
        Depth    24
        Virtual    640    480
        Modes        "640x480@60"
    EndSubSection
EndSection

Section "ServerLayout"
    Identifier    "Default Layout"
  screen 0 "Default Screen" 0 0
    Inputdevice    "Synaptics Touchpad"
EndSection
Section "Module"
    Load        "glx"
    Load        "GLcore"
    Load        "v4l"
EndSection
Section "device" #
    Identifier    "device1"
    Boardname    "vesa"
    Busid        "PCI:1:5:0"
    Driver        "vesa"
    Screen    1
EndSection
Section "screen" #
    Identifier    "screen1"
    Device        "device1"
    Defaultdepth    24
    Monitor        "monitor1"
EndSection
Section "monitor" #
    Identifier    "monitor1"
    Gamma    1.0
EndSection
Section "ServerFlags"
EndSection

言い訳ですが、バックアップはとろうとしていたのですが、途中で消えてしまったので、保存できなかったのです。
お願いします。ubuntu8.04をインストール以来xorg.confはいじってないので、インストール直後のxorg.confがあれば、もどるのかと思うのですが・・・。
おねがいします＞＜

回答ありがとうございます。
下記サイトを参考になんとか修復いたしました。
http://d.hatena.ne.jp/bend_tail/20070429/1177849346
回答内容も同じですね＾＾；
おさがわせしました。