Comodo

Developed by one of the world’s leading IT security providers, Comodo AntiVirus leverages multiple technologies (including on demand & on access scanning, email scanning, process monitoring, worm blocking and host intrusion prevention) to immediately start cleaning or quarantining suspicious files from your hard drives, shared disks, emails, downloads and system memory. Updated virus definitions are automatically downloaded according to a schedule of your choice or by a single click on the 'updater' button. Once installed, Comodo AntiVirus 2.0 beta will unobtrusively sit in your system tray, silently and efficiently defending your system from the latest virus outbreaks.

Homepage: http://antivirus.comodo.com