If you mark yourself as a fan of McAfee on Facebook, you can have a free six month trial of of McAfee Security Software for your PC. This is possible because of an agreement between McAfee and Facebook. According to McAfee:

“Research has shown that up to 78 percent of consumers do not have updated anti-virus, an enabled firewall and anti-spyware, and 48 percent of them have expired anti-virus, the most fundamental protection. So many people without even the most basic protection for their computers are an obvious risk to themselves, but also to people with whom they interact online. The agreement between McAfee and Facebook is designed to address this problem.”

To take advantage of this offer, head over to the Facebook Security page and click the tab titled, “Protect Your PC.”