Thanks a bunch for your replies guys.
The first and best Defragmenter tool I ever used was from Norton Utilities for the Mac back in the day! (1993). Yes, hard to believe, but back then Norton used to have a very good reputation, at least among Mac users. Their Disk utility (part of a package) was able to do a very thorough defragmentation thanks to the fact that it would require you to run it from a separate disk from which you had booted from. This way it could defragment even system files that normally would be open. And once it was done, you could really feel the system way more responsive and faster.
A few years later I had to switch to the PC for work reasons. And noticed that the defragmenters I found they would all do their work while the pc was running, and running from the same system where the application was installed. Which made me very skeptical of their results. But also, I never felt like the system was any better after their work was done, which would further support my disbelief. And ever since I just never gave much credit to any defragmenters. So the one thing that I could feel that was doing something to improve responsiveness was formatting and reinstalling the whole shebang, once a year or so.
But I guess things changed while I was not paying attention. I am glad!
Is there any particular Defragmenter you would suggest, goombawaho?
As for the type of Apps I was talking about, they are mostly from the Open Source community, like Gimp, Scribus, Inkscape, Open Office, etc
Thanks guys,
JDL