Check out this thread - discusses which GFX card to buy. So far:
  • 8800 GTS 512 (had an ATI 3850 but shelved it due to poor game/driver/vista support)
  • i heard that the 9800 is like the 8800, but a hole lot more expensive, i have a Q9300, its amazing, and i have 8gb of ram(4x 2gb 1066), i have a 8800gts 512mb OC, vista ultimate 64, and i can run 5 (at 45, 15, 15, 15, 15 fps), with almost every thing maxed.
I think 1 x 8800GTS 512 would work for you; if you get a mobo will take 2 gfx cards, you can always add another one later.

I've never been happy with ATI drivers either. Nice cards on paper, but RL performance seems lacking (IMHO). As for the manufacturer, some of them like to cut corners and remove certain chips from their cards , which is what I ended up with. So not ASUS... at least not the cards I got!

I have had Leadtek, Gainward and MSI cards with no problems, but not 100% happy with Asus. Lots of folk have EVGA and XFX cards. Just pick one and google it; also check out the manufacturer's forums if you can find them.