video and audio choppiness???

Hey guys,
OK my old bucket needs some help. Its a 600MHZ intel celeron Plll i810 whitney processor. It has 512MB of ram and runs windows 2000. Well my problem is this, I cant have video and sound work in harmony at all. One or the other get choppy. Like just now i tried to play pinball with the computer running some music instead of the default game sounds (btw sounds from whatever is included in the game or whatever work fine) and the sound was chopping. Before i tried to watch a movie on my computer. I install windvd. The sound is fine with no problems but the video was chopping all over the place. What is going on. When i first got this computer it never did that and now it is doing this stuff. Is there any way to make this work in harmony??
-the new tech guy