McAfee VirusScan Plus 2009 Edition with 3-User License for free shipped after a $55 rebate.  Note that it is NOT necessary to own the previous version to qualify for the rebate.  Here is a screenshot for your reference.  This program shields PCs from viruses, spyware, and has a firewall to protect against network attacks.  It also features McAfee SiteAdvisor that warns about risky web sites before users visit them.  Most places have it for over $50.