You could try opening your mouse in control panel and see if there is an option disable mouse acceleration in games, if so put a tick in the box.
It's a long shot, I think Rottevis is right and the P4 is creating a data bottleneck, due to your having sdram.
Also check the game CD for fingerprints or smudges, this can also cause the Cd not to read fast enough.
Again it's a long shot, but maybe worth trying.