control spindown of individual hard drives?

Hello-

Having just seen Al Gore's movie , I was hoping to do a few things to save
some greenhouse gas and some money. I have a couple of internal hard drives
in my Vista system that I don't often access (they're for backup purposes.)

I see in Microsoft's Power Options component of Control Panel that I can set
a setting that specified when to spin down all hard drives after a certain
amount of system inactivity. That's not what I want. I want to be able to:

1. individually control which drives should not spin up when the system
boots or returns from sleep

2. individually control a setting for each hard drive that lets me specify
that after a certain amount of inactivity of THAT hard drive, it will be spun
down

Anyone have any idea if this is possible- either through a third party
(hopefully shareware) utility or a registry setting somewhere?

I have a personal Linux server that runs 24x7 - I just set my internal
backup drive in that machine (which is accessed every day for all of ~15
minutes at 4 am for an automated backup) to spin down after the backup is
complete. I read somewhere that a hard drive requires about 7 watts to run.
Might as well turn 'em off when they're not being used...!

Thanks much, AL