The success of a defragmentation depends on many different factors. As a simple rule of thumb -- the fewer files fragmented compared to your last defrag, the more successful your most recent defrag has been. You must also remember to watch and see if the number of fragments of special files (MFT, pagefile, registry,) have also been reduced. These files are particularly important to your system's performance since they are the ones most often read and written to. Also, if you are running a database, the "db" files should be in one piece to fully optimize file access.
The defragmentation report you enclosed with your question seems good to me, but always remember to watch out for the special files stated above. If they start to fragment heavily, you should consider buying a third-party tool to defragment Windows -- the built-in application cannot effectively defragment these file types.
This was first published in July 2002