KDE

Ubuntu is a Gnome-centric distribution. If you want to use KDE, as I do, add the following to /etc/apt/sources.list:

 deb http://de.archive.ubuntu.com/ubuntu universe
 deb-src http://de.archive.ubuntu.com/ubuntu universe

After an apt-get update KDE is installed with:

 apt-get install kubuntu-desktop kde kde-core