I ran memtest last night, and it got up to 25000% coverage (or maybe it was 2500%, I dunno) without any errors. I wold think that if it was the RAM, that it would have shown up by now.
I've never heard of ram overheating but I guess its a possibility. You know I've never had a blue screen with windows xp I thought it was more stable than windows 2000. Maybe you windows installation is messed up if you have sp2 I forgot what service pack you had.