(This post continues a previous post "Freeing up disc space" and more sharply defines my current status.)

My Dell desktop (with XP) is very sluggish. Example 1: after clicking CAD the Task Manager screen does not appear for 20 seconds. Example 2: Often in using WORD the letters I type do not display as I type them but appear in a burst of letters at once 3 or 4 seconds later. Example 3: when I click the X in the upper right corner to close a WORD file, it often takes 10-15 seconds to do so.

a. I have done a virus scan and things are clean.
b. I have 1 GB of RAM
c. I have 7+ Gb of free space on my C:\disk.
d. The responsiveness of the system when working the web seems better than in working with WORD.
e. When I go to Task Manager (with no apps running), I see that I have 67 processes running and that my CPU uasage is 100%!.

That last point (100% CPU when essentially idling) seems particularly bad.

Do these symptoms suggest what might be going wrong, what to check next?

Thanks.