eSecurity Planet 
A resource for daily information on e-security targeted to IT managers. The site provides users with information from a variety of sources, including experts at security product and services firms, and the consultants who follow the security industry.

Online technology Learning Center: Computer Viruses
This tutorial provides basic information about computer viruses. It explains what viruses are, what they infect, types of viruses, and ways to catch a virus. Information about symptoms of a virus, what to do if you get a a virus, and safe computing practices are given.

Webopedia's "Did You Know?" Article
The Difference Between a Virus, Worm and Trojan Horse.