This content is 20 years old. I don't routinely update old blog posts as they are only intended to represent a view at a particular point in time. Please be warned that the information here may be out of date.
Back in June 2004, I wrote about Microsoft’s introduction to viruses, worms, and Trojan horses. A more detailed document is the Antivirus Defense-in-Depth Guide, which has recently been updated to include the new technologies introduced in Windows XP service pack 2.