CCleaner is a freeware system optimization, privacy and cleaning tool that removes unused files from your system allowing Windows to run faster and freeing up valuable hard disk space. Just in case you feel it necessary, it also cleans traces of your online activities such as your Internet history.
CCCleaner is a fully featured registry cleaner that will allow your computer be free from all kinds of trash. It has drive wiping tool that can wipe all the data from your hard drive or just scrub the available free space. This includes a simple one-pass overwrite or you can use a full-blown 7-pass overwrite, but it will be a much longer process. It also has a cookie deleting feature.
In addition to the above, CCCleaner will empty your recycle bin, delete temporary files, and clean your Registry and it will also back up your Registry before you hit delete. This is an important feature just in case it accidentally removes a crucial component. There's also an uninstaller for removing any program on your computer, but for this I prefer to use the Windows uninstaller.