Is the part about it being "a bitch to use and get going right" based on your extensive use of it a few years back? Linux was a bitch to use and to get going right when I first started using it back in the 1990's.
My point was that I didn't see it destroying cisco/avaya any time soon, due to the nature of enterprise software and the sales distribution channel.
Linux is still not the ideal desktop replacement, even today. It has its place on the server rack, thats for sure, but I don't see it replacing windows any time soon for all uses. Something else might.