computer freezes

[xaznfirez]

lately, my computer has been freezing when playing online games. my computer also freezes when i try to play .rm/.rmvb files 95% of the time. i was wondering what the problem could be.
here are some specs that i know:
AMD Athlon 1800+
512 Ram
Geforce 3 Ti200
Sound Blaster Audigy
I believe the motherboard is A-corp? or something because previously my mb fried and someone changed it for me.

 

[Jae]

try upgrading the video card or the processor, how fast is your memory? (pc2700? pc 2100?)

 

[xaznfirez]

memory is pc2100