Spyware Doctor has Free Real-Time Protection.

Real-time protection works through a feature called 'OnGuard'.
OnGuard runs in the background to actively monitor your system. It includes 'immunization', site protection, popup blocking, browser monitor and others, including defense against known phishing attacks.

The trial version (free, unlimited time) allows use of 'OnGuard' and access to timely updates so will protect against all manner of computer spyware.

However, unlike other programs that offer free removal of spyware, Spyware Doctor requires a subscription to delete malicious files detected in one-off scans.

The full-featured (paid) version was voted by PC Magazine as the 'Best Anti-Spyware of 2005.' However, as part of our least-cost anti-spyware strategy, we will focus on how to make better use of free spyware doctor.

The free version compliments other software recommended on this site, providing the real-time protection other free software lack.

Click here for more information and the free download.