I did the cpu fan paste a few weeks ago and according to the diagnostic software, it never gets hot.
I got the new mobo/cpu/hd in the case today and loaded Vista 32, all the drivers, updates, TF2, Minecraft, etc and it is working great. the little fella is happy and chatting online with friends while playing. I didn't use the new RAM so obviously that wasn't the problem. Maybe I'll add it to mine, for an 8GB total.