I did everything I could think of
I have a HP Pavilion a620n with AMD Athlon 3200+ model and it freezes every time I play a game.
I put in a new power supply now has 500 Watts
A new video card AGP ATI Radon X1650 Pro video card
I even put extra fans in to stop it from overheating even took off the case with a house fan blowing in it.
I did a memtest on it came up with zero errors.
My last idea is the harddrive but I'm not sure
I'm about to take a hammer and start hitting it to see if that works......