Clam AntiVirus (Clam AV) - FREE
Clam AntiVirus is an open source (GPL) anti-virus toolkit innitially for UNIX but now supports Windows, designed especially for e-mail scanning on mail gateways.
It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. The core of the package is an anti-virus engine available in a form of shared library.
Link to Free Download (http://www.theinfostride.com/forum/index.php?action=downloads;sa=view;down=9)