Killing and resurrecting a linux machine

How did I kill it?
- tried to install KDE and found that I prefered GNOME
- removed KDE by aptitude to find that the window manager cannot be completely removed
- completely remove KDE remains by a mass removal of libraries, modules... provided on a site
- reinstall ubuntu-desktop

How it died and revived?
- screen turn black (problem with xserver-xorg or sth like that) --> fine, we can work on generic driver
- no compiz, no hibernation --> fine, ATI driver hadn't been activated
- ATI driver cannot be activated!!! --> fine, just reinstall or re-configure the fglrx package (Video driver for the ATI graphics accelerators)
- still cannot enable desktop effects --> fine, wait for a reboot to see if it works! :)
- finally worked

Don't want to get back to windows!