I don't think it is wise of you guys to trying to get him over-clock. He's a total beginner at this and most likely will damage his system (which is old enough to have lacking some modern safety features).
Maybe later after HE studies the basic principles behind the over-clocking but not now.
Just my opinion.
Equinox: You'll get a massive boost just by getting extra RAM and a dedicated AGP video card. If you are getting more RAM go for the 1GB stick. And a very friendly advice. I would not put more than 60 bucks for the upgrades. Once you start the partial overhaul you'll suddenly realize that you need to have new PSU etc.
I would do the bare minumum now and save the real cash for a completely new comp.
