Date: 2012jun11 OS: Windows Q. Whats the best virus checker for Windows? A. There is Microsoft Security Essentials. Which I understand is OK. Its free if you are willing to undergo the check to make sure you have a "genuine" Windows box. ie not an illegal copy of Window. Not every version of Windows is supported. URLs at Microsoft change often but today it is http://windows.microsoft.com/en-US/windows/products/security-essentials If you don't mind forking over some money, I recommend: http://www.eset.com I have heard good things about Kaspersky http://www.kaspersky.com/