game freeze

[j03y]

i dont know about the rest of u, but both of my pc's freeze ALOT when playing online games. i mostly play bf1942 and mohaa. im not sure y, maybe a heat issue, but my pc will "freeze up" in the middle of play, very annoying. mouse clicks and key strokes are useless, i have to reboot my pc by holding down the button on my tower. i know its not from my vid cards, they are nvidia geforce4 and a radeon9500 pro. im also on a cable connection w/both pc's routed, but the prollems persisted even b4 i got the 2nd pc w/my first one.
anyone out there w/similar prollems or anyone might know what the prollem is? plz help. any suggestions would b greatly appreciated.
1st pc: 2nd pc:
1.2 celeron processor amd athlon 2200+ processor
64mb nvidia geforce4 ati radeon 9500 pro
512mb sdram 512mb ddram
40gig hd 100gig hd

i checked, and my drivers for both pc's are up to date, so that cant b it....
maybe i should get a soundcard? i dont have one for either one, cept for the shitty integrated ones...

again, thanx for any help.....j03y