Microsoft's Tired TCO Toffee
Those with good memories may recall a phase that Microsoft went through in which it issued (and generally commissioned) a stack of TCO studies that “proved” Windows was better/cheaper than GNU/Linux. Of course, they did nothing of the sort, since the methodology was generally so flawed you could have proved anything.
I'd thought that even Microsoft had recognised that this was a very weak form of attack, so I was surprised to come across this....
On Open Enterprise blog.