Free WinDirStat is a disk usage statistics viewer and cleanup tool for Microsoft Windows

(Click here)
WinDirStat can be used to identify large files that can be removed to free up disk space.
WinDirStat reads the whole directory tree once and then presents it in three useful visual views:

•The directory list, which resembles the tree view of the Windows Explorer but is sorted by file/subtree size,
•The treemap, which shows the whole contents of the directory tree straight away,
•The extension list, which serves as a legend and shows statistics about the file types.

•Coupling. Select an item in the directory list: The treemap highlights it; and vice versa.
•Zooming.
•Built-in cleanup actions including Open, Show Properties, Delete.
•User-defined cleanups (command line based).
•Works with network drives and UNC paths.
•'Create disk usage report' option.
•'Submit bug report/Feedback' option.
•Online help.
•setup.exe.
•Language can be set to Czech, Dutch, Estonian, Finnish, German, English, Spanish, French, Hungarian, Italian, Polish and Russian.
Just have a look at the Translation website if you want to help or if you want to know more.
Platforms and Status
WinDirStat is known to run on Windows 95 (IE5), Windows 98 SE, Windows ME, Windows NT4 (SP5), Windows 2000, Windows XP, Windows Server 2003 and Windows Vista.
The current version 1.1.2 is stable.

Downloading and Installing WinDirStat
The program comes in two variants: Ansi and Unicode.
Windows 9x and ME users must use the Ansi variant. All others should use the Unicode variant. Why Unicode? Read about it here.

Download the WinDirStat executables from the project summary page
or from here:

•For all flavors of Windows: WinDirStat 1.1.2 Setup (Ansi & Unicode) (~630 kiB)
•For older releases, as well as their source code, have a look at the Project File List
Sources
WinDirStat is free software published under the GNU General Public License.
View the CVS tree or download the sources (a Visual C++/MFC 7.0 project) from the project summary page or directly as ZIP file or 7-Zip file.