I like to use a program called evidence eliminator - www.evidence-eliminator.com/main.shtml

The program sells for US$74.95 but is available for a 30day free download.

The upside, it will automatically clean all temp files, cache, history, write zeros to all free space on hard drive and a lot more. I've seen a noticable improvement on most all machines after I've run it.

The downside, You have to install the program and uninstall (unless you wish to keep it on the machine). It also takes some time to run since it is a deep clean of the drive.