>Which brings up another question: why isn't there a single product that does both firewall and anti-virus. Some of the issues are plainly conflicts over "who's in charge," for example when scanning an attachment.

I think it's partly history: anti-virus predates the internet and firewalls.

Also, I don't think there is one vendor that "does both" equally well; so you have a component choice ... which I think is good.

In the future, according to the news, you may be able to find a one vendor solution ... but it's still competition that drives product improvements.