Salut,
Aptitude est bien plus parlant!
Accompagné d’un fichier preferences et apt.conf … 
root@pc-2-loreleil:~# apt-cache policy fglrx-control fglrx-driver
fglrx-driver:
Installé : (aucun)
Candidat : 1:10-9-3
Table de version :
1:12-6+point-1+exp1 0
10 http://ftp.de.debian.org/debian/ experimental/non-free i386 Packages
1:12-6+point-1 0
50 http://ftp.fr.debian.org/debian/ sid/non-free i386 Packages
1:10-9-3 0
990 http://ftp.fr.debian.org/debian/ squeeze/non-free i386 Packages
1:9-12-1 0
500 http://boisson.homeip.net/debian/ squeeze/divers i386 Packages
fglrx-control:
Installé : (aucun)
Candidat : 1:10-9-3
Table de version :
1:12-6+point-1+exp1 0
10 http://ftp.de.debian.org/debian/ experimental/non-free i386 Packages
1:12-6+point-1 0
50 http://ftp.fr.debian.org/debian/ sid/non-free i386 Packages
1:10-9-3 0
990 http://ftp.fr.debian.org/debian/ squeeze/non-free i386 Packages
1:9-12-1 0
500 http://boisson.homeip.net/debian/ squeeze/divers i386 Packages
root@pc-2-loreleil:~#
root@pc-2-loreleil:~# cat /etc/apt/apt.conf
Acquire::http::Proxy::bugs.debian.org "DIRECT";
APT::Install-Suggests "false";
APT::Install-Recommends "false";
Aptitude::Recommends-Important "false";
Aptitude::Suggests-Important "false";
APT::Default-Release "stable";
Acquire::Pdiffs "false";
root@pc-2-loreleil:~#
[code]root@pc-2-loreleil:~# cat /etc/apt/preferences
Package: *
Pin: release o=apt-build
Pin-Priority: 995
Package: *
Pin: release o=Debian,a=stable-updates,l=Debian
Pin-Priority: 990
Package: *
Pin: release o=Debian,a=stable,l=Debian-Security
Pin-Priority: 990
Package: *
Pin: release o=Unofficial Multimedia Packages,a=stable,l=Unofficial Multimedia Packages
Pin-Priority: 980
Package: *
Pin: release o=Debian,a=stable,l=Debian
Pin-Priority: 990
Package: *
Pin: release o=Debian,a=testing,l=Debian-Security
Pin-Priority: 90
Package: *
Pin: release o=Unofficial Multimedia Packages,a=testing,l=Unofficial Multimedia Packages
Pin-Priority: 90
Package: *
Pin: release o=Debian,a=testing,l=Debian
Pin-Priority: 90
Package: *
Pin: release o=Unofficial Multimedia Packages,a=unstable,l=Unofficial Multimedia Packages
Pin-Priority: 50
Package: *
Pin: release o=Debian,a=unstable,l=Debian
Pin-Priority: 50
Package: *
Pin: release o=Unofficial Multimedia Packages,a=experimental,l=Unofficial Multimedia Packages
Pin-Priority: 10
Package: *
Pin: release o=Debian,a=experimental,l=Debian
Pin-Priority: 10
paquets pinnés
…[/code]
Au final … 
root@pc-2-loreleil:~# aptitude -s install fglrx-control fglrx-driver
Les NOUVEAUX paquets suivants vont être installés :
fglrx-control fglrx-driver
Les paquets suivants sont RECOMMANDÉS mais ne seront pas installés :
fglrx-atieventsd fglrx-glx fglrx-modules-dkms fglrx-source
0 paquets mis à jour, 2 nouvellement installés, 0 à enlever et 1 non mis à jour.
Il est nécessaire de télécharger 21,5 Mo d'archives. Après dépaquetage, 62,6 Mo seront utilisés.
Charger/installer/enlever des paquets.
root@pc-2-loreleil:~#