If you'd asked me a few months ago...
I would have had an answer. Now everything is changed again, and I have to start from scratch on this question.
Dual core is probably the basic now, but since I'm behind the curve again, I couldn't tell you AMD or Intel. I've always preferred Intel and Intel motherboards in the past for compatibility.
Quad core is the "hot new thing," but it's going to be a while before the software catches up.
