It does sound like a memory issue although it could be a combination of that and a bad install of XP.
If you can I'd try and get a refund on the ram and try picking up a stick or two of Crucial, Samsung or Corsair memory and see if that helps to solve the blue screens.
To lower your temps you might want to try adding a HD cooler, adding another case fan or two or maybe upgrading the CPU fan/heatsink to something like a Volcano 7+ or Delta.