I finally found a great, free, third party defragger called MyDefrag. Current version is 4.3.1. The program is completely customizable via scripts. It has several default scripts for both data disks and system disks which do a great job. I managed to defragment some volumes where Windows defragger left a lot of heavily fragmented files. The program uses standard Windows defragmentation APIs ( which are basically "move this file to that location" ). As such, it's completely safe. I even had my PC do a reboot right in the middle of defragging ( I think the cause was the processor getting too hot ) but didn't lose any data.