AVG Free Edition

AVG Technologies - (Freeware)

AVG Anti-Virus Free Edition is trusted antivirus and antispyware protection for Windows available to download for free. In addition, the new included LinkScanner® Active Surf-Shield checks web pages for threats at the only time that matters - when you're about to click that link.
AVG Anti-Virus Free has these following features:

Award-winning antivirus and antispyware
Real-time safe internet surfing and searching
Quality proven by 80 million of users
Easy to download, install and use
Protection against viruses and spyware
Compatible with Windows 7, Windows Vista and Windows XP

AVG Anti-Virus Free Edition is only available for single computer use for home and non commercial use.