lol a 2700 would be fine. Ok, I'd say get a x2, but one a $200 that's probablt out of the question. So you need a cpu, a mobo, and ram... what's your total budget for all 3 parts?
also do you already have a gfx card? if do is it agp/pcie...
It help to pst what you have, and how much you have to upgrade, and what parts you want to upgrade. Then people can figure out the best price to performance ratio for your setup.