In partnership with McAfee, Facebook offer all 350 million people who use Facebook the ability to download a six-month subscription to McAfee security software at no cost, along with a special 30% discount once the six months are over.
To get McAfee Internet Security 6 month free subscription just enters here and become a Fan of McAfee Internet Security Page
After that you will be asked to select your country ( offer is available to US, Australia, Canada, Brazil, France, Italy, Germany, UK, Mexico, Netherlands, Spain and Latin America residents).
Then create an account and download the Internet security.
However, you need to provide your credit card information, but your credit card will not be charged at this time.
After Your 6-month complimentary subscription, McAfee Internet Security will automatically renew at a special 30% discount), but you can cancel this offer prior to the expiration of your 6-month complimentary subscription. (via)