Sorry, Visvanath, I'm going to have to call you out on that one.
As any good iT person will tell you, the "point of sale" purchase cost of any platform represents a tiny fraction of the total cost of ownership of that platform over the life of the service it provides. In the US, many servers (and the OS's that run them) are purchased at ridiculously cheap prices due to government subsidies and other helps.
Then there's support. Our district has been a Windows-only house for over 20 years. We run something like a dozen websites and severa data management systems, all high volume, on a large collection of Windows servers (virtual or otherwise). None of the technicians in charge of making all that work have any Linux experiece. Hence installing Linux on one box creates a support instance which would require a whole new set of trained skills, maintenance, and enterprise redundancy/disaster recovery designs, all from folks whose days are pretty long already.
Hence, from a total cost of ownership standpoint, it would be difficult to make a case here. Especialy since, right now, I'm getting very good, dependable service out of a WIMP stack.
I do understand the underlying stuff here. Yes, if an IT staff would be willing to stop listening to the industry people and learn some new stuff, chances are they would benefit down the road from the wonderful Open Source way fo doing things. But I'm a high school math teacher with some computer chops, living and Moodling on the good graces of an entire IT department who has no such sensibilities.
Of course, your mileage may vary...