For you, maybe. You see, you have to know how to administer the system in order to be able to do it effectively. We were effortlessly administering computer labs with Linux servers back in '98, when Linux wasn't even mature yet.
As for OS X, Windows TCO is much lower, considering basic costs and lack of applications.
How can you even think that with a straight face? If there's a lack of applications for a purpose, then there isn't even a TCO argument since only one system will do the job. But as far as adminsitering Mac desktops and servers, you will save a whole lot of money.
Basic costs? Whenever Linux people bring up Microsoft's cost, we're always told "purchase price is a small part of TCO." But okay, let's buy a fat dual processor 1U server to serve 50 clients. A Dell 1U with Windows Server 2003 25 user license will cost you over $1,000 more than an equivalent Mac XServe, but you still need to buy 25 more Windows client licenses. Then add to that the fact that OS X Server comes with some great administration tools that even an idiot can use and your Mac TCO goes way down.