8800 For The Win! Hands down. Get the 640mb and dont waste money on any other 8 series unless its a GTX or Ultra
And for a little input: Me and my friend did a test the other day to see how the 8 series stacked up to the 7 series. We used Half Life: Lost Coast video test as our base and maxed out the settings. He had a E6600 and SLI OCd 7900GS's. I have a E6400 and a 640 OCd 8800GTS.
We turned the settings up and let the test run. Even with my crappier processor I destroyed him in the test. I got 108fps as a average and he got around 50 something. So for everyone who recommends 7 series. Just stop it, they arent worth it. They are already outdated because they cant play any of the newer games in DX10 and they dont post #s even close to the 8 series.
You might think your saving money now, but your wasting it in the long run.
Also no one even look at anything less than a 8800. THe other 8 series are crap.
My 2 cents