AVG Anti-Virus

Download, install and use AVG Free Edition and get:
AVG Resident Protection, AVG e-mail Scanner, AVG On-Demand Scanner, Basic Scheduled Tests, Free Virus Database Updates, Automatic Update feature, Easy-To-Use Interface, Automatic Healing of infected files, AVG Virus Vault for safe handling of infected files

About Virus Info page

Everything antivirus, from your Antivirus.About.com guide. Antivirus software reviews, virus help forum, virus hoaxes, virus descriptions and virus software information.

Gladiator Security Forum

Discussion forum containing advice for the latest viruses & alerts.

McAfee Security

Stop Viruses, Trojans, Worms and More!
Keep your PC safe. Automatically checks for virus updates, so your protection stays up-to-date.

Symantec

Virus Definitions, Security Updates, Subscription Support, Virus Removal Tool & Security Checks.

Norman Anti-Virus

A Norwegian-based data security company specializing in developing computer programs for antivirus, antispam, Internet security etcetera.