I'm a computer dork, but it's not actually that hard. All it takes is a philips screw driver and figuring out what parts you need/want. It'll save you a couple of bucks. I'm sure a good buddy will do it for ya if you buy him a pizza or something.

Quick list of things needed not including your monitor:
1. Case
2. Hard Drive
3. RAM
4. Video card (might be smart to get a card with two video outputs so you can add another screen now or later)
5. Operating System (Microsquash XP Home should suffice.)
6. Motherboard

You can take out your floppy drive and use it on the new computer, if you actually use it. I don't know why, but I always have a 3.5 inch floppy drive in my computers, but use it like never.