Rusting In Peace said:
Why do you think the hard drive isn't going to be used? Presumably things need to be paged out to the hard drive if you're doing a fail number of calculations. How much ram do you have? What memory consumption are you seeing?
Argubly yes keeping the drive spun down will prolong it's life. However constantly moving states for long period of time will probably be detrimental.
I have 4GB and rarely does it go over 25%