Mildly O/T. Hard drive power down

Is there a software way to force a drive to power down?

XP powers down drives after x amount of time (Control Panel -> Power
Options). I have mine set to 20 minutes. I have 1 internal hard disk where I
store all my admin files (patches, software installs, drivers etc) and
backup files. I only use the drive every now and again (maybe once a day),
but would like to turn it off when finished. I can't be bothered spending
time and money on an external casing.