CCleaner is good. I like Registry Mechanic a little better, possibly because the interface is a little cleaner. OTOH, Registry Mechanic isn't free, unless you find it free after rebate, which happens at Fry's Electronics maybe twice a year. 😎
Registry Mechanic is from PC Tools, which is now owned by Symantec. They sell the same program as Norton Utilities. The difference is, if you need tech support, someone answers the phone at PC Tools' toll free number. :thumbsup: