This is Windows Explorer add-in, which adds ability to view folder's content size as well as file size. Now you needn't any utility to find a folder where you waste disk's free space, just open your Windows Explorer and all secrets before your eyes.
Hi guys, I've tried ViewFolderSize, it's limited capabilities and not easy to install. Our company just purchased Advanced File Manager, and I think it's the most useful and handy toolbox. Allows easy monitor folder size + reporting capabilities+many other useful functions. Just try it. Just look at screenshots here: http://www.advexsoft.com/products/advanced_file_manager_sc.html
May be you should try ViewFolderSize Pro. It's quite more fast, customizable, useful. And even it's work on WinXP Pro x64 edition (as well as on WinXP Pro on my second PC).
You can get it here - Moveax web site