The address worked for me. Here's the link for the file: hdapm
Some info from that website...
It can be used to:
* eliminate "clicking when idle" noises exhibited by some laptop hard drives
* make a drive save more power and spin down more aggressively that in does with the default OS settings.
MacOS 10.4 or 10.5. ATA/SATA hard disk with APM support. Does not work with USB or Firewire attached drives.