Yes, it's been hashed over what seems to be countless times. Basically my take on it is the X850XT has a slight performance advantage overall, winning more often than not and sometimes by quite a bit. But the 7600GT would take some games and has a feature set advantage. They are close enough that if it were my money and they cost the same, I'd go with the 7600GT, especially one of the higher factory clocked versions.
And the feature set advantage really IMO does not mean it will last any longer. When games someday come out that require PS3.0, then I think both these cards will be too weak to enjoy such a game anyway. But the 7600GT will let you get to experiment with OpenEXR HDR like Oblivion uses, and that's a nice setting to get to play around with if the card has the power to use it. The other side to this story is the 850XT will easily beat the 7600GT in Oblivion with FSAA and therefore no HDR. So the X850XT would allow for higher detail settings.
Anyway, I wouldn't fault anyone for buying either card, I only fault those who claim that one is the clear choice for everyone.
By the way, below are some games you can click on and compare them. These charts support my own feeling that the X850Xt is a little higher perfomance. Even the 6800U OC 425/1100 pretty much edges out the 7600GT in nearly every test in this review, although I hear that the 7600GT handles HDR a little better from someone here who has owned and benchmarked both. And the 7600GT will OC better than the 6800U also as the 6800U core is already near it's limit.
http://www.digit-life.com/articles2/digest3d/index.html