This is what the Disk Defragmenter looked like in XP.
This is what it looks like in Vista.
I do not even need to explain why the Vista version totally sucks. You have no idea what's going on behind the scene, nor do you have any hint as to how far the defragmentation has progressed and how much longer it will take.
As one of my best lecturers once said, a good program needs to be verbose, and that means that it keeps the user informed of what it's doing.