Virus scanning recommendations for computers that are running Windows Server 2008, Windows Server 2003, Windows 2000, Windows XP, or Windows Vista
I knew this was out there, had to find it again! Now to post so I can blame myself for not remembering. A similar title would be “my guard dog ate my homework”. As in, depending on the configuration of your virus scanning software, you might have an impact on the performance of your server.
A few other links in regards to this topic.
KB309422 - Guidelines for choosing antivirus software to run on the computers that are running SQL Server http://support.microsoft.com/kb/309422