http://www.malwarebytes.org/lp/lp4/?utm_source=bing&utm_medium=cpc&utm_campaign=search-brand-us
free version
This is not anti-virus software. It finds and removes a lot of things that AV software does not such as PUPs - Probably Unwanted Programs. PUPs can contains anything from annoying adware to malicious processes that steal identity/etc.
I'm leery of Russian sites simply because my wife manages an electronic fraud dept. in a bank. The things I hear at night startle me.