You guys should rememebr that the Internet 2.0 will be out in 10+ years and security problems might not be as crazy as the original internet is.
Security issues will always be a problem, but keep in ming there is a such thing as the intranet. Why does the company be totally on-line with their OS? They can be a online OS on their own system.
Not to sound like a commercial, but every system has its down side. Having your OS on the internet, intranet, darknet or extranet could be no more dangerous than having a computer connected to the internet, intranet, darknet or extranet.
I'll admit though that now instead of taking 2 steps, you now only need to take one to get to their OS... but with most data shared through some sort of LAN, WAN or whatever, you can get at it anyway.
Besides, this is where its going anyway. Just ask Microsoft in the batter against Netscape. The internet will be the next OS.