Check out http://www.virusbtn.com for more info about all things virus related. Particularly useful are the VB100 Award archives. You can check the performance of almost every antivirus program on the market in different OS over more than two years.

I really like NAV Corporate for its central management features. An administrator can handle all updates from a cetral location. Also, no matter what unsubstantiated performance claims some may make, there is nothing more effective.