The best set of forums I've run into for answering AMD questions is
AMDMB - now renamed PCper.
FWIW, I've bought three XP-mobile 2600s from NewEgg - the slowest one is running 200x12.5 - and they all needed relatively minimal voltage to get there (1.6 to 1.7V), so you're probably not going to be generating as much heat as whatever you're overclocking with now. This is about as close to on-topic-for-procooling as I can get this.
I
assume you're going to be using a nvidia chipset motherboard to overclock with? There
have been multiplier issues (essentially one bit missing) with some of them - most notably the Asus A7N8X series, so you'll find yourself limited to multipliers of 12.5 or lower. There's a "wire trick" to get around this - or you could just pick a motherboard without the problem. Go read up on AMDMB if this sounds unfamiliar.
Overclocking any processor is a crapshoot, of course, but I either got lucky or the XP-M 2600s are pretty much all good.
Bob
PS: Yow - just went to Newegg, wondering how much these processors are now (always a bit depressing when you see how much you could have saved by waiting six months or a year). The price has actually gone
up a couple of dollars. Guess the word got out about these...