another thing that is greatly forgotten or not known by the casual user is the Virtual Memory/Page File...
to defragment the area that is in use for that you have to go into system properties, advance tab, perfomance-settings, advanced, virtual memory, change...
once there set choice to no paging file or move the paging file to another partition...
once the current paging file is changed...
then do a defrag of the partition/drive it was on...
thus defragmenting the Virtual Memory/Page File portion of the drive/partition....