WinDirStat - 631KB (Open Source)
WinDirStat is an open-source disk usage analyzer, designed to help you identify how much disk space you are using and what you are using it on. It will analyze any drive or directory that you choose and then provide you with a visual display of all your files. WinDirStat assigns each file type a color depending on how much space it is taking up, allowing you at a glance to see which file type is taking up the most space. So for example, the files taking up most of the room on your drive or directory are blue by default.
The advantage of WinDirStat is that once you know where you are using the most disk space, you can then decide where you want to slim down and where space can be saved. Thanks to the numerous features in WinDirStat it is easy to manage your files, this includes a setting to automatically delete files without the use of the Recycle Bin. With its intuitive interface, WinDirStat is really easy to use and you won't have any problems getting to grips with any of its functions.
You have the choice of viewing your files in three different ways: