Here's a site which let's you hear those sounds you never want to hear from your own drive

http://datacent.com/hard_drive_sounds.php

Well the link seems to have an error on it now.

Will wait a bit, and if no joy will remove it.

there are a few here:
http://www.cybertechhelp.com/forums/showthread.php?t=120507

believe or not,,those sounds could be dust,,bad reformat,,i prefer to wipe off drive.
also a poor defragmentstion...consider cleaning from the inside out..

Just looked and my link is back