So, last night I tried to get XBMC running on my previously headless server (Debian 6). Installed xserver+xorg, gnome and gdm3, and tried to get nvidia drivers for my old Geforce 6800 ultra to run. I got it working, but only in predefined resolutions (I need 1920x1080). I tried forcing 1920x1080 but that's when it all went crazy. The resolution is right, but it extends outside my monitor, and I get a "zoomed in" viewport of 640x480 or something. The "viewport" follows my mouse though. As you can guess this is not really good enough.
Today I installed Ubuntu 12.04 and get the same result, what can it be?