Free Anti-Virus: Microsoft Security Essentials

Microsoft Security Essentials is a free anti-virus program. All of the free anti-virus programs out there have usually pretty quickly fallen out of favour with me, in particular the previous community darling AVGFree. Having a free option from Microsoft, that performs extremely well with minimal resource usage, is a boon. For privacy reasons, you might want to opt out of the Microsoft SpyNet. Opting out is a very manual process though, with instructions here Download Microsoft Security Essentials