CCleaner is a powerful program that will clean all of your unused system files and will also clean your internet history. I use this program every week to remove all the crap from my computer. CCleaner can also be used to fix registry files and remove programs.

Download CCleaner here

Once you have unzipped the folder and installed the file you should see a program that looks something like this:

The analyze button will show you the files that it would delete, and the Run Cleaner button will just delete the files. I usually click the analyze button and then click the Run Cleaner button.

If you click Registry on the left, it will offer you the option of checking for errors in your registry files and it will fix them for you.  Be sure to have CCleaner backup your registry just in case something were to go wrong.  It would look something like this:

The Tools option on the left will allow you to uninstall any program. So if you ever have a problem uninstalling something the usual way then CCleaner can help.