Have you tried "analog playback"?
Tools > Options > (tab) Devices > Properties (for the drive you're using) > "Playback Settings" > "Analog"
Troubleshooting Playback in Windows Media Player for Windows XP
http://support.microsoft.com/default...b;EN-US;306317
Resources for Troubleshooting Sound Problems in Windows XP
http://support.microsoft.com/default...b;en-us;307918