I am constantly getting viruses what is the best FREE virus protection for my computer?

[Froggie]

Avast is currently rated THE top free anti-virus program by both PC Magazine (UK) and PC World (US), both for prevention and cleaning. Some links in both Facebook and Craigslist are known to have embedded viruses, which might be your problem. With your record of getting infections, you should run your protection scans daily, or even more frequently whenever you will be away from your computer for a while. YOU are the cause of the infections ... clicking links or opening Spam mail. Some malware can install itself just by opening a web site - it's called a 'drive-by'.

These sites off excellent scanners to remove the more complicated spyware/malware that Avast might not catch, but they must be run in Safe Mode. If you buy the paid version of MBAM, it has constantly-running protection.

Scans several times in Safe Mode with Networking, which catches and cleans far more than normal boot-up mode. (Hold down the F8 key when the computer screen first lights up, until you hear a beep or see a new dark screen. Then use the arrow keys and Enter to get to Safe Mode with Networking) Be sure you are logged in as an Administrator. Re-boot into Safe Mode for each scan, with the CD/DVD in the drive so you can execute the anti-malware programs from there. If you use a flash or thumb drive, it could also get infected, but it can be used for most scans safely.

When the scan runs clean, update all tools used before (except Housecall) and run again with the updated files. First run your regular anti-virus program, then you should scan with several different anti-malware programs, since they catch different things, but only one should run constantly.
http://housecall.trendmicro.com/ (an online scanner, always up-to-date)
http://www.malwarebytes.org/mbam.php (free version, update before running)
http://www.superantispyware.com/ (also free, update before running)

Once clean, remove all System Restore points (Start > Programs > Accessories > System Tools > System Restore > delete ... small, in left panel) for XP or (Start > Right click Computer > Properties > System Protection), select any hard drives with protection on, press Configure..., and turn off system protection. Then re-enable it (deletes all restore points). before re-booting for Windows 7. This prevents any malware from re-installing itself. Of course, once you re-boot in Normal Mode, re-set a new System Restore point right away. If you have detected malware on your computer, change all of your passwords after cleaning up the infection.