Seriously though, if you're not a gaming fanatic with a ig budget and you're looking for a good price/performance ratio then the 7600 or above would do well. Up to January I was using a 6600GT and I found only Oblivion and to a lesser extent Medieval II gave it trouble even at 1024*768 resolutions. Even then they were playable. And that was with some ridiculously low level of Video RAM.
If you check the 8800 reviews you'll notice the GTX model is overpowered anyway - on many games its FPS levels out since the current generation of processors and bus speeds just can't get data to it fast enough (one of the reasons I like it since it offers a lot of future proofing). If I was not upgrading, I'd have waited 6 months but I needed my 6600 elsewhere.
By the way it's AMD not ATI these days