I found the Xubuntu, which is a complete GNU/Linux based system with an Ubuntu base. It is a new project, born in April 2006. So now we have Ubuntu, Kubuntu, Edubuntu and Xubuntu.
Xubuntu is s lighter, and more efficient than Ubuntu with GNOME or KDE, since it uses the Xfce Desktop environment, which makes it ideal for old or low-end machines, as well as thin-client networks.
Edubuntu is customised for classroom use. The idea is that as an educator you’ll be able to set up a computer lab, or establish an online learning environment, in an hour or so — then administer that environment without having to become a fully-fledged Linux geek.
Kubuntuis a user friendly operating system based on KDE, the K Desktop Environment. With a predictable 6 month release cycle and part of the Ubuntu project, Kubuntu is the GNU/Linux distribution for everyone.
Ubuntu is shiped with the latest Gnome release and is the base of the Kubuntu, Edubuntu and Xubuntu.
Xubuntu is shipped with top quality packages from the Ubuntu archives. Xubuntu will use, as far as possible, GTK2 applications, ensuring maximum efficiency. If you wish, you can install any KDE or GNOME application on your Xubuntu desktop system, as it shares the Ubuntu main and universe package selection.
Here are the relative links.