Mal, to up a 2500+ to a 3200+ all you do is move the FSB from 166>200(it runs like DDR.....so 166=333, 200=400). If you do this, and then get an Nforce2 board (LOVE the onboard sound...would reccomend the deluxe version of the board) which is suppost to be the best board for that CPU. Also, if you get PC3200 ram (runs at 400mhz) it's suppost to sync w/ the CPU and give you a great boost in speed. This is what I have done on my stock machine (no extra cooling yet) and it is stable as can be. Of course, I have yet to do any hardcore gaming on it yet, but it's been up pretty solid since I put it together on christmas.
After I put in my intake fans, and put on my HS and get a fan for it, I am gunna up the speed a lil' more....get it to like a 2.6ghz. Once it's there (and I hear it's pretty easy to achieve those speeds w/o much cooling and still run great) I think that's all the OC'ing I am going to do on it, it's all ya really need IMO. If you have any more questions about it Mal, I'd be glad to help. Just PM me 🙂.