Well judging by your motherboard disregard all suggestions made to you, you're AGP buddy. I'd recommened this card:
XFX 256MB 256-bit 6800XTreme
I just bought the 6800XT, it runs things like a breeze, I've almost got WoW maxed out on 1280x1024 resolution, everything but AA and multisampling or something is maxed out, runs good, only got 1gb of ram though the game still goes right, 2gb will do teh trick and that's coming soon!! Battlefield runs perfectly on High Quality settings, lots of things are running now as opposed to my 9600XT beforehand!! GO XFX 6800XT!!
Edit: My bad, just realised that you have 6800GT, well now that I see that, the only thing I think that would beat it is the 7800GS maybe, not really sure.