Here is a great utility for visualizing your hard drive to find what’s taking up all the space – WinDirStat and you can get it from http://windirstat.info/
I have tested it in Vista and it works very well and is extremely fast and did I mention that it is FREE…
It displays folder sizes, file sizes and shows you a color coded diagram of the locations of files on your hard drive. You can see below all the blue square are MP3 files and they are pretty much in the same location. Nice!!!
Other similar tools:
TreeSize Personal – costs $20+ (http://www.jam-software.com/treesize/treesize_personal.shtml)
FolderSizes – costs $50 (http://www.foldersizes.com/?gclid=CPb8nYW93owCFRGsGgodbCDv6w)
Here is a screen shot of WinDirStat