Something is running in the background....have you checked for spyware or viruses? Do you have an older version of Office installed that also installed FindFast by default? That's an indexing program that comes with Office or stand alone Word that you can disable in Control Panel and delete the shortcuts to it in the Startup folder. Also, check RUN/MSCONFIG/STARTUP to see what items are loading during the boot and uncheck the obvious ones that you know you don't need starting up immediately that run in the background.
I am experiencing a problem in XP that I never had in ME. When typing email,Word,or just about anything including this request, the letters appearing on the screen are often behind my keystrokes. I am not that fast a typist. But, regularly, I will have to wait for several seconds for letters to catch up on the screen that I have already typed. The cursor just freezes in place. This is very annoying! Any suggestions?