No Auto Updates, and hard drive running all the time

Hello....I've just done a clean new reinstall of XP SP2. I know for a fact
and from experience, that automatic updates will kick relatively quick and
start collecting updates, usually within 15-20 minutes of new install.
However...it has been 2 days now and it won't kick in. I have checked and
rechecked the settings and it is set on, "Keep my computer up to date" and
"Download updates and notify me when they are ready to install.

In the meantime I noticed the hard drive is running non stop. Just like if
it was retrieveng updates, but there is no Icon in the sys, tray. I looked
in the Task Manager and there are no processes hogging the system (System
Idle is 99% for the most part) and there are no applications running. Is
there some other way to investigate what is making the hard drive sweat so
much?

Thank You
Roger