I have an SB51G with a 2.4 P4, WD SE and IBM 60GXP drives, a DVD/CDRW combo drive, GF Ti4200 (too be replaced by an ATI Radeon 9800 Pro soon), and an M-Audio Revolution. It runs great, and reasonably cool, even with those two hard drives there to heat things up, so I wouldn't worry too much about the heat. My only suggestions to you are as follows:
1. Ditch the Audigy. First, you might want to give the onboard audio a try, since it's not that bad. And if you don't like it, get the M-Audio Revolution, which I like MUCH better than the Audigy 2. That, and one less customer for Creative is good news to me.
2. If the price difference isn't too great, spend the extra money to upgrade to the Corsair 3200XMS. Since Intel's using an 800MHz FSB now, I bet even their non-P4 "C" chips will have nice overclocking headroom--the better RAM will make sure that they're not the thing holding it back. If you're worried about heat, I was able to get my 2.4 up to 2.8, but that was a little too hot for me, but at 2.6, it was great, so overclocking is definitely possible--even in these tiny things.
3. XP Pro is much better than XP Home. It's $50 more, but it's probably worth it, especially if your school is running a Novell network. XP Pro is just has more networking options, and I've had a much easier time setting up friends' computers running Pro than Home.
4. GamePC is expensive. While I've never had anyone build a system for me, I think ABS
is cheaper, and they have good ratings (quite a bit better than GamePC).
Anyway, I live in a dorm room too, and it's nice having such as small computer...especially since I have two rather large towers sitting under my desk too... It's also cool to be able to put the thing in its bag (which is very handy) and take it on the plane when I go home.
Good luck with your purchase...hope it all goes well.