In my case, I need a video card that works best with flight sims, namely FSX and X-Plane 9. Tradition says it has to be an nVidia card.

Both flight sims are texture-heavy. Even with 512mb video ram, the 8600GT is starting to swap out textures esp with FSX modded to the max. So, I'll need an nVidia card with lots of video ram along with the most system ram I can afford. The latter can wait when I'm finally allowed to assemble a quadcore pc.