Ubuntu 에서 apt-get install 이 안 됩니다 ㅜㅜ

VMWare 에 Ubuntu 를 설치해서 .. 부팅한 후 ..

패키지를 몇 가지 인스톨 하려는데 .. 아래와 같은 증상을 보입니다 .

설치하려는 패키지의 종류에 상관없이 .. "꾸러미를 찾을 수 없습니다" 는 메시지가 뜹니다 .

왜 그런 것인지 좀 알려주세요 ㅠㅠ

# sudo apt-get install libqt3-headers libqt3-mt-dev build-essential bin86 kernel-package libstdc++6
 
꾸러미 목록을 읽는 중입니다... 완료
의존성 트리를 만드는 중입니다
상태 정보를 읽는 중입니다... 완료
E: libqt3-headers 꾸러미를 찾을 수 없습니다

인터넷은 지역 케이블 .. 쓰고 있고 ..

Ubuntu 상에서도 정상적으로 잘 되고 있는 걸 확인했습니다 .

아래는 /etc/apt/sources.list 의 내용입니다 .

#deb cdrom:[Ubuntu 8.10 _Intrepid Ibex_ - Release i386 (20081029.5)]/ intrepid main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.

deb http://kr.archive.ubuntu.com/ubuntu/ intrepid main restricted
deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid main restricted

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

## 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://kr.archive.ubuntu.com/ubuntu/ intrepid universe
deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid universe
deb http://kr.archive.ubuntu.com/ubuntu/ intrepid-updates universe
deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid-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.
deb http://kr.archive.ubuntu.com/ubuntu/ intrepid multiverse
deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid multiverse
deb http://kr.archive.ubuntu.com/ubuntu/ intrepid-updates multiverse
deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid-updates multiverse

## 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://kr.archive.ubuntu.com/ubuntu/ intrepid-backports main restricted universe multiverse
# deb-src http://kr.archive.ubuntu.com/ubuntu/ intrepid-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 intrepid partner
# deb-src http://archive.canonical.com/ubuntu intrepid partner

deb http://security.ubuntu.com/ubuntu intrepid-security main restricted
deb-src http://security.ubuntu.com/ubuntu intrepid-security main restricted
deb http://security.ubuntu.com/ubuntu intrepid-security universe
deb-src http://security.ubuntu.com/ubuntu intrepid-security universe
deb http://security.ubuntu.com/ubuntu intrepid-security multiverse
deb-src http://security.ubuntu.com/ubuntu intrepid-security multiverse

kr.archive.ubuntu.com 은 가끔 접속이 안 되는 경우가 있을 수 있다고 해 ..
ftp.daum.net 으로 바꿔보기도 했지만 .. 그렇게 해도 안됩니다 .

대체 왜 안 되는 걸까요 ?

P.S. 그리고, /etc/apt/sources.list 는 apt-get 을 설정하는 파일이라던데 ..
sources.list 의 설정 내용을 변경한 후 .. 이를 적용하려면 어떻게 해야하나요 ?
재부팅 해야 하나요??