Oh no!
 We can't have someone download a free “patch”(Microsoft Security Essentials) when the OS vendor(Microsoft) advises them to do so can we?
 Sooo...Tell me then..did you do this download from Apple to patch a massive 88 security holes in your OSX when Apple advised you to or not?
Apple plugs 88 Mac OS X security holes
 Apple today released one of its biggest Mac OS X security updates in recent memory, covering a whopping 88 documented vulnerabilities
http://blogs.zdnet.com/security/?p=5916
 Oh no! 
Does that mean that I can't get you to run without your anti-virus program then? LOL ...
 I guess the Macintosh users are the only ones confident enough in their own Mac OS X to run without any anti-virus programs at all... :-)