Although Windows 7 does a good job of keeping your hard disk defragmented if you have added and delete a lot of small files, for example many MP3 music files, in a short amount of time then Windows might not be keeping up with your activity. Watch this video to see how you can check for fragmentation of the data files on your hard disk. If the tool reports more than 10% fragmentation then it is a good idea to go ahead and defrag your hard disk. This video shows you how.