If your hard drive appears to be filling up fast, it’s probably due for a good clean out and one one quick way to regain space is to check for a clear out any duplicate files, especially if you have a large amount of music, photo and video files.
Clone Spy is a free program that can seek out duplicate files even if they have different files names. It will then either delete the extraneous files or move them to a folder for you to check and delete yourself which is probably the safer path to take.
Clone Spy runs on Windows XP, Vista and 7 and is free to download from http://www.clonespy.com.