I hate to ask, but has this got anything to do with Amiga gaming?
Well.. erm.. You can play Quake on an Amiga these days :-D
Anyway... IT can be hard to get usefull help from the overcrowded Window / gamers websites out there..
@Zanthras
It may be because of bad GL and/or GFX drivers.. Try different Drivers for you Geforce card, go for the official nVidia Detonator
