If you believe that the Windows program uninstaller deletes all the program, then you are very wrong. Very rarely does this uninstaller (or the programs` own unistallers) delete the folders where these programs were stored, so over time you end up with a load of empty folders on your hard drive.
To delete them you need Remove Empty Directories 2.1, which checks minutely the whole hard drive locating and deleting all empty and useless folders (even if they are hidden or protected).
For every folder deletion it creates a log (with the name of the deleted folders) for you to consult, and even restore folders that you want to keep.