There are many Via KM133/KM266 motherboards that use the S3 Savage KM133 video onboard. The problem is that there is a glitch in the XF86Config that prevents that video chipset from running at anything other than 640x480.

The fix is to add the option "UseBios" with a value of "no" in the /etc/X11/XF86Config file. This would be great to get fixed in Knoppix. Right now, all my web-kiosk boxes end up with a black screen (no video) after X starts up.