One of the most popular and effective anti-spyware solutions, and the personal edition may be downloaded free of charge. A full scan is recommended once the program is installed and updated.
This is another popular and very effective product, also completely free of charge. Spybot offers some other additional tools for advanced users to perform additional troubleshooting, and offers an immunization option that prevents many malicious programs from being able to install. In addition to detecting spyware and adware, Spybot also detects many keylogger, backdoor, and malicious remote control programs that are often installed when a computer is compromised.