I'm going to be going off to college in about a month and two weeks and I'm going to be getting a new desktop computer to bring with me.

I'm probably just going to put the computer together myself with parts that I buy.
Problem is, I'm pretty much clueless when it comes to what is actually good inside computers.

I want it to be able to play games (namely, Battlefield 3 when it is released.) and do all the crap I would need from a computer in college.

What I'm asking is what parts I'll need and what I should get.