I have a Gainward 7600GT Silent FX and I can't say I have noticed any problems with using Windows XP 32, Windows XP 64, Vista 64 ultimate and Suse linux using the out of the box drivers. Though with the Vista 64 I had to upgrade the drivers from the those which which came with the card on a CD, to the then most recent internet downloaded drivers [ about a month ago ] as there was a problem with the aircraft in MS Flight Simulator 2004 breaking in to angle shapes but the updated drivers solved that.
Articolo: Silenzio Totale per la Tua Scheda Video (mag '06) - PC Silenzioso
Best and Warm Regards
Adrian Wainer