PII 940 or..
the triple core 920...
But seriously...
...at this point I would say Quad Core although I am reluctant to recommend the C2Q. I think that if you're getting a whole new build just spend some more on the cheaper i7 and make it last you longer. Although differences between the i7 and the C2Q are little to none right now, I can guarantee you programmers are already looking for a way to fully utilize the capabilities of the i7. However, if the money really is a factor, you have pretty much no choice but to go with the C2Q.
And AR, AMD does RULE!!!!!!!!!!!!!!!!!!!!!!!!!!!