I have written about free disk defragmenters for Monitor magazine. Although there are some decent free defragmenters out there, but lets be honest, commercial competition in a good step in front.
My personal favorite is Raxco Perfect disk that really makes a difference once you run it. I tested it thoroughly few weeks ago when I tried to shrink my main partition (to make room for Ubuntu, I'll blog about that later) with tools build into Windows Vista. PerfectDisk cleaned up space for me that other free and non-free products just wouldn't. It worked perfectly.
Raxco PerfectDisk 2008 line just came out and they are having a sale until midnight tonight. With the code GET2008NOW you get 20% off any product!
I just bought PerfectDisk for Windows Home Server that gives me licence for home server + 1 client for $40 - 20% = $32 / 24 EUR. It's same price as if I would buy 1 professional licence, so you basically get server licence for free. That's an excellent deal in my book!
This is not ad or sponsored post. I don't get any provision of sales or anything. I'm just cheering for a cool tool and great deal.