Hello!
I would rather have a fully premium (paid for) antivirus or internet security suite protecting my computer rather than dealing with free programs, that have little protection value.
Strong, premium antivirus programs are more recommended and fare best when run in a hostile environment, such as poor browsing choices, downloading, etc.
Please check out either one of two choices and make a "premium" decision, one that can save you from getting infected:
avast! Pro or avast! Internet Security: http://www.avast.com/free-antivirus-download
Kaspersky Antivirus or Internet Security or PURE: check out the K logo in my signature to be taken to a product selection page.