By now most people have likely already upgraded to Windows Vista Service Pack 1, but one of the smaller feature upgrades might have passed most people by: You can now configure automatic defragmenting for All drives, as well as defragment all of your drives at the same time.
Set Automatic Defrag Options
Launch Disk Defragmenter by typing dfrgui into the start menu search or run box (or you could just search for defrag in the start menu or control panel)
Once you are there, you will notice the new “Select volumes” button that wasn’t there before Service Pack 1:
This will launch a dialog where you can choose which drives should be automatically defragmented at the scheduled time:
Note: Vista SP1 most likely already scheduled all your drives to be defragmented by default so there’s really nothing to do but make sure you have the latest Vista Service Pack!