sound stutters and mouse arrow is choppy

I have two computers in my office that act really weird. One is an Intel 450 with 256 mb of ram. The other is a 1.3 GHz with 496 mb of ram. Both computers run Windows 98. No other Win98 machines in my office do this. The mouse skips around the screen and the sound waves stutter. This behavior is especially prevalent when first loading the desktop after logging in. This also occurs to music cds if you try opening a program while the music is playing. The sound stutters. I have already tried messing with virtual memory settings, disabling all startup options in msconfig. Nothing seems to help. These are brand new fresh installations.