Before we give any suggestions for core components, the question to ask is this - how much are you willing to spend?

I'm also going to ask if you have things like a keboard and mouse (which won't add much to the final price), monitor and speakers (which will add a few hundred dollars), and which OS you want (personally, I think you'll need more than 2gb of RAM - 4gb would keep you more comfortable, but to take advantage of the full 4gb you need a 64-bit OS).