Dudes, i think it just matters what kind of Nvidia or ATI you have.
Of course, if you upgrade from a Nvidia fx 5200 128mb to an ATI x800 pro, you're going to say that ATI is way better. And if you upgrade from an ATI Radeon 7200 128mb to a searing Nvidia 6800 256mb overclocked, the Nvidia is going to be way better.
From my perspective right now, the 256mb ATI X700 i just bought, upgraded from my nvidia fx5200 128mb, is freaking amazing. What a difference. In fact, it's slightly better than when I tried out an Nvidia geforce 6600, 256mb, on the same machine. I'm able to bump up resolutions on EVERY game (including Battlefield 2 and FEAR, the top-of-the-lines) and have no problems.
But the point is, depending on what you can afford, whatever card has the better stats is going to be the better card. I could only afford the $120 x700, not the $400 nvidia 7800.
