FWIW...
I tend to hammer systems by making repeated edits of large files so my drives become fragmented very quickly, and I've been looking for a decent defragger for some years. The MS-supplied defragmenter is pretty well useless, IMHO.
I used Defraggler on a 136G NTFS drive under XP PRO SP2 to defrag all the files it reported as fragmented the first time and then analyzed using Disk Defragmenter, which kept showing a report of fragmented files that turned out to be folders (and Disk Defragmenter doesn't even try to defragment those).
I gave Defraggler the folder names and it defragmented them very rapidly. I followed up with another Disk Defragmenter analysis, and the "files" no longer showed up as fragmented. A few rounds of that and I ended up with a drive that even Disk Defragmenter reported as unfragmented (although the free space was fragmented).
Done in a fraction of the time that Disk Defragmenter takes.
I've also tried Diskeeper, Norton Systemworks (back in 2000 Norton's product was good, but it's been adulterated since then), O and O Defrag Pro, and PerfectDisk, and Defraggler comes out best in my estimation.
Personally, I don't care if the free space is fragmented - I'm not so much a perfectionist that I want my drives pristine at all times
So my only niggle is that the default Analysis only seems to check for fragmented files; if it also highlighted fragmented folders as well (so that I didn't have to explicitly go looking for those with another tool), or alternatively gave a choice to defrag the entire drive including folders plus/minus free space, I'd be a very happy camper
There are very few pieces of software that impress me, but Defraggler is now part of that select group.
Best,
Peter