Dell XPS 700 2.4gHz Core 2 Duo 6600

[Georg]

It might be you have an Anti Virus program or tool with an option activated causing it to monitor/viruschecks in realtime all file accesses/reads/writes. That slows down things a lot.

Or a tool that maintains some database.

A tool called FileMon (google for it) which is similiar to SnoopDos on the Amiga might give some hints.

I once had a rootkit virus which also caused massive slowdown.

[Yisrael48]

REINSTALL XP

[RRunner]

If the problem is most notable during startup, try de-fragmenting your registry. I have noticed dramatic performance increases (especially at startup) after optimizing the registry using Registry Mechanic.