On the many sites I've visited regarding XP audio tuning, i never came across this trick.
We all know that the process manager is handy to detect services and applications eating away at our precious CPU cycles, but when streaming audio (either with samplers or DAWs), its critical that your HD controller be freed of any other I/O too!
Now MANY MANY programs and services on XP periodically access your disks in your back. From antiviruses, firewall logs, to much more obscure things.
So start XP, download :
Install, Run, and dont touch anything! ... Just watch.
I'm sure you'll be able to track and shut down most of the executables that access your DAW's disks
(i even shut down things accessing my system drive too often)
dont know what a particular exe is? Just search for it and you'll find it on one of the many "is that exe a virus" sites.
Please report your findings!