free antivirus from Microsoft

Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It's easy to tell if your PC is secure - when you're green, you're good. It's that simple.

DOWNLOAD LINK FROM HERE ------ 32 BIT

DOWNLOAD LINK FROM HERE ------ 64 BIT