Microsoft Vista's built-in disk defragmentation tool is supposed to run in the background unnoticed. But, I don't like leaving my PC on when not in use (I turn it off overnight and turn off the power strip it is connected to). So, it usually runs when I am using Vista. So, every now and then, I run it manually to defrag the disk. The problem, like much of Vista, is that the disk defragger is user hostile. The screenshot above is the sole interface to the app.
Once started, it tells you: "This may take from a few minutes to a few hours". That's it. No indicator of any kind, graphical or text.
FYI: I've been using the freeware Defraggler app to defrag XP and Vista PCs for a while now. Seems to work well.