Savage Erazor is a straightforward tool that will quickly locate and delete redundant files, freeing up valuable hard drive space.
The program is a little more aggressive than some of the competition, not only deleting the contents of specific folders (\Temp, internet caches and so on), but also wiping out files elsewhere, based solely on their extension (*.ERR, *.TMP, *.DMP and many more).
There are risks involved in this approach, because you can't be sure that you're not wiping out something important. It will free up more drive space, though, and Savage Erazor protects you against potential problems by moving its erased files to the Recycle Bin. If anything does go wrong then you can quickly restore everything and get your system running smoothly again.
Still worried? Savage Erazor is reasonably configurable, so you're able to tell it not to delete particular file types. And you can also point the program at custom files and folders that you know are safe to delete, which should help you free up even more hard drive real estate.