As much as I don't like microsoft, this argument is strange. For one, you talk about the email services, but you know outlook isn't the only email service that gets exploited by worm writers.

Also to take down the internet you would have to take down the backbones like another poster mentioned, which would take a huge, huge planned attack because of the sheer bandwith of each one. They atleast push out 14GBPS, and thats low end for bandwith for backbones. My guess is far higher than that.