Go to Start -> Run -> type dxdiag and press Enter. (Windows Vista: Press the Windows Key (the key with the Windows logo on your keyboard) + R (at the same time). Type in DXDIAG and press Enter or click 'OK', this will open the DirectX diagnostic tool.) Click on the button that says Save All Information. Save the file to your desktop and name it DxDiag.txt. Open the text file with notepad and
copy/paste everything listed under System Information, and everything listed under Display Device all the way down to Driver Date/Size.
Download HWMonitor (choose the correct one for your system, top left side)
http://www.cpuid.com/hwmonitor.php
Run it after your computer has been sitting idle for a few hours. Take a screenshot of your temps and attache it here. Do the same after playing the game for awhile so we can see your temps.