Help on com that keeps rebooting when gamin
 

My computer is only 2months old and it's already givin me a headache by rebooting itself everytime i play a game for roughly 10mins. However, it does last longer when i on the air-conditioner and update my OS to the newest version (windows xp sp3). But it still reboots after around 2-4hrs of gamin..

My pc parts consist of E8400 3.0ghz, 8800GT OC, 4GB DDR2 ram, Coolermaster Elite casing (with one inflow and one outflow fan), Antec Earthwatts 500W and 320gb sata II Hitachi.

Temps are Cpu 35-50degC, Gpu 51-70degC and hard disk 28-40degC.
All the temps are taken when gamin (eg. Gears of War). Are these temps really SOOO hot that the com had to reboot so as to protect my components from burning? Or is it an issue of underpower of the PSU? I really need some guidance..Thanks~~ :)