Nou, FrSu, hetgeen de anderen aangeven is ook niet zo moeilijk, maar is via de terminal.
gedit /etc/apt/sources.list
En dan opent zich het bestand en ziet er zo ongeveer uit:
# deb cdrom:[Ubuntu 9.04 _Jaunty Jackalope_ - Release Candidate i386 (20090414.2)]/ jaunty main restricted
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty main restricted
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-updates main restricted
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-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://nl3.archive.ubuntu.com/ubuntu/ jaunty universe
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty universe
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-updates universe
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-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://nl3.archive.ubuntu.com/ubuntu/ jaunty multiverse
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty multiverse
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-updates multiverse
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-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://be.archive.ubuntu.com/ubuntu/ jaunty-backports main restricted universe multiverse
# deb-src http://be.archive.ubuntu.com/ubuntu/ jaunty-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 jaunty partner
# deb-src http://archive.canonical.com/ubuntu jaunty partner
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security main restricted
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security main restricted
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security universe
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security universe
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security multiverse
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-proposed restricted main multiverse universe
deb http://nl3.archive.ubuntu.com/ubuntu/ jaunty-backports restricted main multiverse universe
deb-src http://nl3.archive.ubuntu.com/ubuntu/ jaunty-security multiverse
Of je kan het ook vinden via Locaties>Computer>Bestandsbeheer>Etc>apt>sources.list, maar dat is net hetzelfde als Systeem>Beheer>Softwarebronnen.
En zo kan je nog wat meer wegen vinden denk ik.
Nu, wat je lijst betreft: je kan alles waar er 'Broncode' achter staat eigenlijk uitvinken, wat dat zal je niet direkt nodig hebben, denk ik zo.
En wat die launchpad bij jou komt doen weet ik ook niet, misschien ergens iets apart gedownload/geinstalleerd buiten om Synaptic?