ちなみに/etc/apt/sources.listの内容は以下のようになっています。

# deb cdrom:[Ubuntu 10.10 _Maverick Meerkat_ - Release i386 (20101007)]/ maverick main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://archive.ubuntu.com/ubuntu natty main restricted multiverse
deb-src http://archive.ubuntu.com/ubuntu natty main

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu natty-updates main restricted multiverse
deb-src http://archive.ubuntu.com/ubuntu natty-updates main

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu natty universe
deb-src http://archive.ubuntu.com/ubuntu natty universe
deb http://archive.ubuntu.com/ubuntu natty-updates universe
deb-src http://archive.ubuntu.com/ubuntu natty-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.

## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://jp.archive.ubuntu.com/ubuntu/ maverick-backports main restricted universe multiverse
deb-src http://jp.archive.ubuntu.com/ubuntu/ maverick-backports main restricted universe multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
deb http://archive.canonical.com/ubuntu natty partner
deb-src http://archive.canonical.com/ubuntu maverick partner

## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
deb http://extras.ubuntu.com/ubuntu natty main
deb-src http://extras.ubuntu.com/ubuntu natty main

deb http://archive.ubuntu.com/ubuntu natty-security main restricted multiverse
deb-src http://archive.ubuntu.com/ubuntu natty-security main
deb http://archive.ubuntu.com/ubuntu natty-security universe
deb-src http://archive.ubuntu.com/ubuntu natty-security universe
deb http://archive.canonical.com/ natty patner
deb-src http://archive.canonical.com/ natty patner