Not really a good comparision, considering the 9800 series is a over a years old. It should be 6800 ultra vs x800 xt. However, that topic has been discussed over and over. If your a doom 3, far cry, world of warcraft fan then go with nvidia. If your a half-life fan then go with the ati. If your going for ati, my suggestion is go for the x800 xt, not the 9800, just for future proof.