Microsoft has released a thorough public document titled Solutions for Security - The Antivirus
Defense-in-Depth Guide. This is a 90-page document detailing the current threats and background, how to deploy antivirus protection for corporate use and how to control virus outbreaks. It's a pretty good document (yeah, we helped review it).

The file is available for download from Microsoft Technet. I just can't figure out why a PDF file has to be installed before it can be viewed.