http://consumer.diskeeper.com/diskee...=1&Aeid=&Apid=
Buy it, use it, love it. I used to not defrag, but after using this, I won't ever go back. You'd be surprised at the performance boost. Windows Defrag is a flaming piece of poo, by the way.
You can probably find a version of Diskkeeper Lite (free version) if you look around as well. It works just as good, but takes longer.