UPDATE: I'm sad to say Spy bot is not longer a recommended piece of software.  Bloat and lack of detection has added to this programs demise.  Please check out Malware Bytes for your free spyware problems. 

I have been using this software for years and continue to recommend it to everyone. Its very easy to use and its free. This software has not been bloated and keeps getting better with age.  Spybot compares your files to a large repository of spy ware and ad ware.  It also had a good immunization database which protected you from sites that are hazardous to you.  This latest version provides an even smoother updater so that you run it with the latest list of spy ware. 

Check it out here: