Stand-alone defraggers like MyDefrag organize/optimize PC files better than the standard defragger that is built into Windows. Windows 7 definitly does a better job than Windows XP at optimizing your PC.
Since creating the MyDefrag tutorial there have been other free defraggers that have come up. Currently I would recommend Disk Defrag by Auslogics over the older MyDefrag.
http://www.auslogics.com/en/software/disk-defrag/#overview