Veja um exemplo de arquivo /etc/apt/sources.list real que disponibiliza praticamente tudo que você precisa para uso num desktop Debian.
Veja as configurações do APT que utilizo para um desktop baseado em Debian 3.1 Sarge.
Decorridos mais de meio ano do lançamento do Debian GNU / Linux versão 3.1 (Sarge), alguns pacotes mais atualizados para desktop começam a fazer bastante falta.
Para uma instalação mais fácil, e de muitos outros pacotes interessantes, veja os arquivos preferences e sources.list que utilizo no desktop hoje.
Package: *
Pin: release a=stable
Pin-Priority: 800
Package: *
Pin: release a=testing
Pin-Priority: 101
Package: *
Pin: release a=unstable
Pin-Priority: 99
Package: *
Pin: release a=experimental
Pin-Priority: 9
Package: *
Pin: release a=sarge-backports
Pin-Priority: 200
Package: openoffice.org-l10n-pt-br
Pin: release a=sarge-backports
Pin-Priority: 999
Package: openoffice.org-help-pt-br
Pin: release a=sarge-backports
Pin-Priority: 999
Package: openoffice.org-dictionaries
Pin: release a=sarge-backports
Pin-Priority: 999
Package: openoffice.org-gnome
Pin: release a=sarge-backports
Pin-Priority: 999
Package: openoffice.org
Pin: release a=sarge-backports
Pin-Priority: 999
Package: clamav
Pin: release a=sarge-backports
Pin-Priority: 999
Package: clamav-freshclam
Pin: release a=sarge-backports
Pin-Priority: 999
Package: libclamav1
Pin: release a=sarge-backports
Pin-Priority: 999
Package: clamav-base
Pin: release a=sarge-backports
Pin-Priority: 999
Package: lsb-base
Pin: release a=sarge-backports
Pin-Priority: 999
Package: firefox-dom-inspector
Pin: release a=sarge-backports
Pin-Priority: 999
Package: firefox-gnome-support
Pin: release a=sarge-backports
Pin-Priority: 999
Package: firefox
Pin: release a=sarge-backports
Pin-Priority: 999
Package: mozilla-firefox-dom-inspector
Pin: release a=sarge-backports
Pin-Priority: 999
Package: mozilla-firefox-gnome-support
Pin: release a=sarge-backports
Pin-Priority: 999
Package: mozilla-firefox
Pin: release a=sarge-backports
Pin-Priority: 999
Package: debhelper
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-kernel-common
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-glx
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-glx-dev
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-kernel-source
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-graphics-drivers
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-graphics-modules
Pin: release a=sarge-backports
Pin-Priority: 999
Package: nvidia-kernel-2.6.14-2-k7
Pin: release a=sarge-backports
Pin-Priority: 999
# official repositories or mirrors
deb http://security.debian.org/ sarge/updates main contrib non-free
# deb file:/var/cache/apt-build/repository/ apt-build main
deb http://http.us.debian.org/debian/ sarge main contrib non-free
deb http://non-us.debian.org/debian-non-US/ sarge/non-US main contrib non-free
deb-src http://http.us.debian.org/debian/ sarge main contrib non-free
deb-src http://non-us.debian.org/debian-non-US/ sarge/non-US main contrib non-free
deb ftp://ftp.br.debian.org/debian-non-US/ sarge/non-US main contrib non-free
deb http://ftp.br.debian.org/debian/ sarge main contrib non-free
# unnoficial repositories
deb http://www.debian-multimedia.org/ sarge main
deb http://download.videolan.org/pub/videolan/debian sarge main
deb-src http://download.videolan.org/pub/videolan/debian sarge main
#deb http://ftp.debian-unofficial.org/debian sarge main contrib non-free restricted
#deb-src http://ftp.debian-unofficial.org/debian sarge main contrib non-free restricted
#unofficial repository with with BACKPORTED packages maintained by the official
#package maintainers. Reliable, but still unofficial. Read the faq at their site.
deb http://backports.debian.or.at/backports.org/ sarge-backports main contrib non-free
deb ftp://sft.if.usp.br/debian-volatile/ sarge/volatile main contrib non-free
# if you try to mix packages from testing with stable, being stable the main version
#enable these repositories
## tentativa de misturar pacotes de versoes, sendo stable a principal
#deb http://http.us.debian.org/debian/ testing main contrib non-free
#deb-src http://http.us.debian.org/debian/ testing main contrib non-free
#deb http://ftp.br.debian.org/debian/ testing main contrib non-free
#deb http://security.debian.org/ testing/updates main contrib
#deb http://secure-testing.debian.net/debian-secure-testing/ testing/security-updates main contrib non-free
#deb-src http://secure-testing.debian.net/debian-secure-testing/ testing/security-updates main contrib non-free