the hd3850 performs with an 8800gts 640mb (sometimes better), thats like a $300 card card, proof enough that the hd3850 is the best bang for the buck card currently out
but if you turn into a gamer soon, you're really going to regret not getting a hd3850, because it trounces any 8600 in terms of bang for the buck and Performance
but if you are getting an 8600gts, you might as well get a 7950gt or 7900gs instead, because they perform better