I am an old time user of spacemonger, which is very useful to find what is getting so much space on a hard drive.
Yesterday, from the Tekzilla show, I got the suggestion to use Windirstat. The screenshot seems to be very neat, so I tried it.
Let me tell you something: the screenshot of windirstat is the ONLY thing that is better than spacemonger.
First, windirstat scan several directories at the same time. That is bad and makes the procedure very slow because the hard drive head is going to one place to another to scan every folders and there is a big lack of performance here. Spacemonger analyse it in 1 thread so the hard drive head is not moving, and the scan is a lot faster.
Second, the result displayed in the virual map is not usable in windirstat. It represents EVERY file of your disk, it is very slow to render, and it's impossible to select a whole folder from this view, you can only click on a single file. In SpaceMonger, it shows you a representation of the biggest files or directories from a zone, not every one big like 4 files in 1 pixel. And you can zoom in by double-clicking to view more, and it's easy to select a containing folder, not its content, from the graphic view of spacemonger, which is impossible to do with WinDirStat.
So, forget windirstat, use spacemonger. Their latest version 2.1 is offered at 24.95, but they also offer their old version 1.4 which is free, certainly less performant or beautiful, but works really fine, and can be used on Windows Vista and Windoed 7 even if it was created for Windows XP.
You should try Directory Report
It looks just like the MS-Explorer but shows the size of all the folders
Both Windirstat and Spacemonger use confusing tree maps
http://www.file-utilities.com