Note that not using the inbox defrag.exe can (and, frankly, will) screw up the information in the ReadyBoot cache. This means that whilst you're OCPD tendencies are assuaged by moving all files sequentially on the disk

, you are actually slowing down the boot and prefetch processes due to misses from the ReadyBoot cache needing to be serviced and files read in from the disk in a different location than it was previously (thus resulting in an additional seek and read head movement). Also, layout.ini (which stores this information) is not generated/updated every day (by default it's every 3), so it could be awhile before the system catches up with what the defrag program did.
It's not critical, but you should at least know all of the ramifications of what you're doing if you don't use a defragmenter that knows to update layout.ini (and how to do it). The only 3rd party defragmenter that updates layout.ini properly is PerfectDisk, and I have not seen any indication from others that they bother with this - it doesn't mean there aren't other 3rd party defragmenters that update layout.ini, but I have not seen any public indication or documentation on any other than PerfectDisk that this is done.