I have always had problems with my windows directory's growing to a huge size. It started with windows 95 then 98 then 2000 and xp. Windows 7 however is absolutely huge. The windows folder itself with out program files is 21.4 gigs...add the program files and other windows files and it is a whopping 32 gigs. My question is why is it so large and what can I do about it. At the rate this is going I will be out of space in now time.
In Windows Vista and 7, The Windows directory is not actually as large as Explorer tells you it is. In these versions of Windows, there are a large number of NTFS junctions (hard links) in the Windows/WinSxS directory which point to other files on the disk. Explorer will dereference these junction points when calculating the size of the directory, so a single file may be counted 2, 3, 4 or more times. (ref.)
Run WinDirStat and see if you can find any unusually large files. The program displays all of your files graphically:
Sometimes you can find a large corrupted file that is entirely useless.
Why? Each new version of Windows includes a larger set of features, which requires more programming. This often results in more .DLL and other program, data, and other files. The Windows Registry also increases with size over time, not to mention the "Temp" directories that don't always get cleaned up properly and tend to accumulate more and more data over time.
Many other Operating Systems are also getting larger as the degree of complexity increases and the feature-sets grow.
Another factor is that newer user interfaces include higher resolution graphics, which usually also require more disk space for storage.
What can you do about it? Make sure your hard drive is large enough (21.4 GBs is far smaller than the typical 250 GB and 500 GB drives for sale these days in new computers, so you probably don't need to worry too much about this for new computers anyway), unless you wish to take the time to determine which files are safe to delete first (not recommended because this can result in serious instability problems or just prevent Windows from booting entirely).
If you are using offline files check the client side cache. c:\windows\csc [it is hidden]. If it becomes corrupt it expands at a great rate until it fills up your c: drive.
To fix it turn off offline files, reboot, empty the csc folder and turn offline files back on. It will sync with the server.