Sgt / Peerless
Unfortunately I am not a Intel man prefer AMD myself. I did a little research based on the information that ante1 has provided in this thread. I do not think ante1 is overclocked I do not think the CPU is overheating. From my experience have built and broke several computers. I love to break things according to my wife. ante1 either has a bad stick of memory and it may be overheating or a driver issues. That is why I recommended having the memory tested. If the memory is good I would still add another 512mb if you want XP to sing you need it. Any way if the memory does test good then it is probably a driver but usually if it is a operating system conflict you will get the blue screen of death. Check out the links below and see if you can come up with any more ideas.
CPU/
http://indigo.intel.com/compare_cpu/...&culture=en-US
CPU operating Temp/
http://processorfinder.intel.com/scr...ALL&CorSpd=ALL
Motherboard/
http://www.msicomputer.com/product/p...Neo-V&class=mb