I'll tell you what. You can have the best solution known to man kind but the real challenge is getting all the users to be Net Smart. A virus definition is never going to stop the 'open the email - from Aus Post' they just don't get it. Then you have the rogue users that don't authenticate onto the domain, so you have no idea if there Definition files are up to date, or they are even meat to be there.
It goes on and on. The best protection is to stop non authenticated devices on the net. How many of you corparate guys let your users bring their I-Pads, I-phones etc to work, and then access internet resources?
We went through this with AMEX where there where over 100,00 devices to manage. It doesn't matter how good you are. We used to hire 'Hacks' to work with us to stop intrusions. Half of our forum here wouldn't even know if they have been 'violated' and that's the beauty of what they do, stealth.
Even the best in the business still clearly state they are on the back foot and in regards to some viruses they can take Months to even get an update out.
Back to sensible and safe.
Do not open the 'you have won 1 million dollars email. Ensure your company knows that, educate, and to be honest I am more worried about port scanners so make sure the firewalls are up to date.
And you can Pooh Pooh me as much as you want. I work with some serious government players around the data security area looking after AFP and Immigration (Boat People) medical records, there is not much more important stuff than that.