work automatically, but I'm not sure. When I upgraded from single to dual-core, my XP installation got kinda messed up (running really slow), but there could have been other things to cause this. So there's a possibility that you'll have to reinstall/repair XP, but you probably won't have to resort to that, I was just impatient and didn't know where to turn.
And by the way, I'm just a high school student.
This forum is overall pretty young. There are members far more knowledgeable than me. But I've gone through pretty much everything that you're going through now hardware-wise. I made the jump from 1 to 3GB of RAM, single to dual-core, tampered around with clock frequencies, and I had to mess with the power settings once. So this is all very familiar territory.