noblues
as far as I know defrag only deals with files in the FAT and sys files.
When the files are moved they tend to go at the start of the drive and fill up the disc space from there. If there is any "deleted" data there is no way of knowing where it is on the disc and they may or may not be over written by the defrag process.
A bit hit and miss ifyou want to destroy data!!
regards
CK