Microsoft has complete the process to bought an antivirus company (which I never heard about it), and has published oficially at some of their websites:
--- Microsoft Completes Acquisition of Enterprise Security Provider Sybari Software ---http://www.microsoft.com/presspass/press/2005/jun05/06-21SybariCompletePR.mspx
The Sybari's products are focus to the security in messaging services, it will apply inmediatly to Exchange 2003, this will help to avoid the problems with viruses, worms and spam.
Via Channel 9