One thing that has always been missing from Windows Explorer is the ability to see how large a folder is. How many files are in a folder and sub-folder would be nice, but seeing the total space taken would be best. Well, the Folder Size Explorer Extension tries to do the latter:
Folder Size Explorer Extension adds a new column to the Details view in Windows Explorer. The new column shows not only the size of files, but also the size of folders. It keeps track of which folders you view, and scans them in the background so you can see complete size of all files within the folder. It’s very useful for cleaning up your disk. Once you get used to having that information available, a directory listing simply looks incomplete without it!
I’ve installed it on my XP system and it seems to run well. Not surprisingly, in my Porgram Files folder, the Office 2003 folder is the largest.
Check it out at http://foldersize.sourceforge.net/