it all depends on what your looking to do with it. Hardcore gaming? Casual gaming? Cad work? How much are you looking to spend? AGP or PCi-e?
Honestly… you could spend upwards of $2000.00 on a video card. There are alot of options out there. If you want directX 10, then you’ll probably want the 8800, if not… then you could go an SLi route and spend less with similar performance