Computer freezes constantly!!

hi i hve a p3 with a 800MHz pc 20gb hd and 128mb ram with windows ME
ive been running it for a pretty long time now and now the computer keeps freezing for some reason i think its becuase of some hardware or my hard drive so i got a new hard drive and installed it with windows xp and it was still freezing...
any1 knw y it is freezing??

 

well check the power supply if it works properly
check your ram it may be damaged
check your graphic card

if all the above fails then discinect evetrgibf from the motherboard leave the grapgic card and boot.
if the system works add a device and boot again.
if there is a faulty device these way you will pint point it.
well it will take a whileeeeeeeeeeeeeeeeeeeeeeee
good hunt