I'm in the process of trying out O&O Defrag V8.0 Professional and am rather impressed. I've been using MS's defrag utility but have grown increasing annoyed with it. I mean, why can't I defrag two drives at once? Well O&O does just this (actually it defrags all four of disks at once). It also doesn't give me grief when my drives are nearly full. It might be a bit pricy at $45, but if you move a lot of files around, it might well be worthwile.