TreeSize Professional is a powerful and flexible harddisk space manager for Windows 200X / XP / Vista (32 and 64 Bit). Find out which folders are the largest on your drives and recover megabytes on your disks.
TreeSize Professional shows you the size, allocated and wasted space, the number of files, 3D charts, the last access date, the file owner and permissions, the NTFS compression rate and much more information of several folders or drives you choose. It also lets you search drives, entire servers or the entire network for old, big, temporary and duplicate files.

Features:
# Visually track down disk usage and see the size of all folders including their subfolders and break it down to the file level.
# Several exporting and reporting possibilities: Printed report (showing the directory structure), Excel, HTML, XML, text file, clipboard.
# The integrated fully customizable file search helps you to find and archive the largest, oldest, obsolete and temporary files, e.g. invalid shortcuts or files owned by a non existant account.
# You can search multiple drives, entire servers and even your entire network neighbourhood. The search results can be exported, moved or deleted.
# Duplicate file search, optionally with MD5 checksums
# Statistics about file types and file owners on directory level. Additionally, it is possible to filter the file system tree on the left to a certain user or file type
# TreeSize Pro is able to save the data to an XML file and to load it again later.
# A saved XML file can be used to compare it against the current version of the file system branch. The difference between the two scans will be displayed and makes it easy to see which folders have grown.

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Thanks for the post!
When I need to clean up some space on Vista I also use Junk Files Cleaner from Digeus:
http://www.digeus.com/products/junkcleaner/index.html