The only thing you can really do is disable all unnecessary services.
Plenty of guides on the web to tell you what to close.
Change Windows to prioritise services over applications (in My Computer->Properties)
Only other thing that could make a difference is HD speed make sure it's a 7200RPM one.
If your just using if for MP3 playback consider running SlimServer (
http://www.slimdevices.com/su_downloads.html)
It's cross platform and open source and will stream to your player application of choice.
Particularly the DSL (damn small linux) based SlimCD if you want to get best performance
http://www.herger.net/slim/detail.ph...kategorie=slim.
It's a live cd so fairly easy to test