my sound is choppy!! help!!!!

recently my sound has been choppy when i try to listen to an mmp3 file or wav file or even streamind media through real player or quicktime. there seems to be some conflict with my pc’s on board sound,but i cant find the problem i have done varioustrouble shooters on windows ME but no luck at all
this also happened while i had windows 98
what can i do about this problem?should i just throw my pc out the window??? help!!!!!