Facebook is now directing users who think their computer might be infected to sites where they can get free antivirus software.

The Malware Checkpoint for Facebook sends people either to sign up for Microsoft Security Essentials or McAfee Scan and Repair. Mac users are referred to an Apple Security Updates site.

Facebook already notifies users when the site detects a possible malware infection on an individual machine, and provides these users free antivirus software to clean up the infection. The social network has now opened up its anti-malware campaign to all users in order to them them proactively protect themselves, according to a post on the Facebook Security page:

If you are concerned that your device may have been infected by malware, you can visit http://on.fb.me/infectedMSE or http://on.fb.me/infectedMcA to be self-enrolled in either our Microsoft Security Essentials or McAfee Scan and Repair malware checkpoints... 1. The McAfee option will download a small program onto your Windows computer to perform a one-time scan of your system for malware. It will not interfere with your existing anti-virus or other security products. After it scans your system, it will give you the option to automatically or manually remove the files it flags as malicious. 2. The Microsoft Security Essentials option is a full anti-virus product. Upon download and install, it will add anti-virus software to your computer that will continue to protect your system with the latest anti-virus signatures from Microsoft.

Last year, Facebook added new security features, including Login Approvals and warnings when users are about to get hit by clickjacking and cross-site scripting attacks or malicious links on sites. Earlier this year, the site began offering free antivirus assistance and improved its external blacklist system to protect users from malicious Web sites.