Whenever I use my Maxtor Onetouch 3 I have quite a loud whirring noise with it.

This is probably normal, some hard drives are noisier than
others, and the tend to get louder as they get older.

The old Maxtor drives were very loud and quite unreliable,
but I have not tested their new ones.
(once burned, twice shy)

Personally I prefer Seagate. I have 8 Seagate drives in a single
machine including a RAID, and they perform very well.

They are also much quieter than Western digital or Maxtor.

Finally, whirring is OK, grinding is not. If it is louder than
you feel comfortable with, erase is with a secure file wiper,
such BC wipe by Best Crypt, and then take it back to where
you bought it (give them hell)

Also if the drive suddenly got a lot louder than it was before,
this could mean that the spindle bearings are gone and you
need to replace it before you loose all data on it.

Also, if this is used only as a backup drive, as the manufacturer
intended, then you should power it down when you are not using it.

Before turning of the power switch on the drive, though, make
sure that Windows has completed and committed all the
pending write-back cycles. Click on the green arrow on
you task-bar /icon tray: and click "Safely Remove Drive"
windows will then tell you when its safe to turn off the drive.

Hope this helps, please rate my answers.

Martin