One thing that's unavoidable with Windows is many duplicated files which serve little or no purpose.
However, did you know it was possible to find and replace at least those files that have been duplicated without going through them manually? Programs such as Duplicate File Finder can search files byte by byte and compare them so that you can have a better idea of which files you need and which ones you don't. The interface clearly presents you with the path names and locations of those files which appear to be duplicated. It's then up to you to decide which ones are duplicates and which one's aren't. The good thing about this program is that it's incredibly quick at searching - you'll wait for less than a minute for Duplicate Files Finder to return results. In addition, you can interactively delete files or create links and refine searches to the minutest of details.
A nice utility for cleaning up your hard drive or removing those files that you never even knew existed on your hard drive.