So.......
Start with the guts. The processor and motherboard, and work out from there, memory, video, etc.
Processor: Intel or AMD? Dual or Quad core? i7?
Motherboard: I have an Asus. I have heard good things about them.
Memory: DDR3. At least 4gb to handle 64-bit. But it is expensive, so DDR2 for budget. Maker? Corsair, reviewed
HERE.
PC Perspective
(http://www.pcper.com/) is a hardware review site. Might be a good place to start. They also have a podcast every week on
TWIT.TV (Leo Laporte's Internet Tech TV site).
I'm going to follow along with you, I want to get a new comp in the next 6-8 months and, for a change, I'd like to build one.