On older computers this noticeably slows things down.
As it only speeds up searches it is not necessary.
IN XP Right Click on My Computer, right click on Drive C.
Right Click on properties
Ensure the tick is removed from "Allow Indexing Service to Index this disk for fast file searching.
The problem with this is that on a reboot it may default bak to having a tick in the box. If so try this.
To disable the indexing service:
1.In the "Start" menu, choose "Run."
2.Type "services.msc" and press Enter.
3.Scroll-down to "Indexing Service" and double-click it.
4.If the service status is "Running", then stop it by pressing the "Stop" button.
5.To make sure this service doesn't run again, under "Startup Type:", choose "Disabled."
To disable it, go to the Control Panel and click Add/Remove Programs. Click the Add/Remove Window Components. Simply unclick the Indexing services and click next!