Windows WinSXS folder

Optimizing WinSXS folder
used to repair software installations, not safe to simply delete, although theoretically windows should ask for the install DVD if it can't find files.

http://www.vlite.net/

use Windows Installer CleanUp utility to remove references to uninstalled or unused files

Replace duplicate files with hard links to reduce redundancy
http://www.digitalvolcano.co.uk/dupe.html