A deficiency that I have found with quite a few of the low end defraggers is that they do not include in the list of partitions to be defragmented those partitions which do not have a drive letter. Sad to say that defraggler which is otherwise such a great little program also has this deficiency. Some might wonder why you would want such a partition. Well one very good reason is to prevent "fragmentation contagion" from temporary files in a cache from spreading throughout ones relatively static files. So you can set aside a small partition just for temporary files of this type, and simply "mount" it in an otherwise empty NTFS folder that has been created for temporary files. The great thing about this is that you can mount this *same* temporary file partition in any number of folders which are intended for storing this type of temporary files (A knowledgeable user will be aware of a number of these folders - such as browser profile folders or "User/Local Settings" folders). Doing this keeps all these temporary files which are created and deleted with gay abandon from causing fragmentation amongst more static files. It is generally the case that if you find a reason to mount a partition in an empty NTFS folder, then it is usually desirable (even if only to prevent newbie user confusion or conserve drive letters) to un-assign the drive letter from that partition. It is the case that this type of partition is often the very one that you would want to defragment the most often - and it is not possible to do it without assigning it a drive letter first, then defragmenting it, and then un-assigning the drive letter again. So an improvement to Defraggler would be to include in the list of partitions to be defragmented those which don't have drive letters assigned. Please note that even Microsoft's rudimentary defragmenter offers this facility when run from the computer management console (right-click "My Computer", select "Manage", then "Disk Defragmenter"). Unfortunately apart from this capability it is a particularly poor defragmenter!