In that case try turning off the Find fast indexing

Click Start |(Settings) | Control Panel.
Double-click Find Fast.
In the Index for documents in and below list, click the first item.
On the Index menu, click Delete Index.
In the Delete Index box, click OK. When you are prompted to delete the index, click OK.
Repeat the latter two steps until no more indexes are listed.
Click the Index menu. If the Run When I Log On check box is selected, click it to clear the check box.
On the i]Index menu, click Close and Stop. If you are prompted to stop Find Fast, click OK.

See if that reduces your HDD activity