You're going to get some FreeBSD (and other *BSD) users riled up with that one (Hotmail and Yahoo, for example, are too notable services that did - in Hotmails case until well after the Microsoft acquisition - or do - in Yahoo's case - use FreeBSD extensively)
Imagine the costs of getting a service oriented internet company up and running in a world where the only choice is Windows and IIS.
I wonder how much longer it would take sites like Youtube to scale to their current size.