Computer keeps restarting

This is my sons computer... he is having problems with his computer randomly rebooting. He plays WoW... and it happens alot in WoW. Today before he went to work, it happened while just sitting in Windows.

He has the ability to monitor the following temps with a Cool Master Cool Drive:
Case
CPU
Video Card

These are his idle temps
Case: 24.5C
CPU: 35.0
Video: 38.0

It is a P4 3.0, 1Gig memory Windows XP Home Edition (registered and up to date with updates).

Are there any programs I can run to see if one of these is unstable? Or does anyone else have any other suggestions. We have run Adaware and McAfee Virus scan and nothing was found. We took the computer outside and blew it out with a portable air mattress inflater to remove dust.

Thanks in advance
Lamedog

 

Those are decent idle temps, but what does it run at under a load?

Also, how many watts can his PSU put out?

 

I can't get into his WoW account... was hoping I could find a program to "test it" while he is at work". It is a 420W PS.

 

Have a look here for some bench marking programs. Freeware ones should be OK. Look for ones that will put cpu, memory, video under pressure for starters.