CCleaner. It's completely free to download AND use. It also has a neat program to remove all .tmp, chkdsk, temporary interntet, history, prefetch, etc files all in one click.
Most of the registry cleaners offer free download but want to charge you to remove what it finds after installing it. Not CCleaner.
http://www.piriform.com/ccleaner/downloadThe pay version is only for support. click on one of the free download locations below the big button.
