Dave -

Windows 7 (and Vista) should defrag automatically, in the background, if you haven't changed the settings. I haven't seen enough Win7 to tell you where it is, but in Vista if you open Control Panel and put defrag in the search box it should tell you where it is, and it should have a "run automatically" box checked that tells you when it runs. If you leave the box checked, you should never need to run it manually - and you should never see it run since it works in the background.

John