Yup, no surprise here, just more FUD from Microsoft, since TCO is about the only argument they have left against OSS.
Arguments that Linux is free... are incorrect..
.. with such a rich diversity of software applications and hardware devices now on the market, companies can achieve tighter integration by using Windows.
But you'll still need to buy those extra applications and pay for support/maintenance whether or not you need it. If you don't pay for on-site support (which you'll need to wait for) you'll need to dedicate a fraction of a headcount for self-support. And beyond a certain amount of time (5 years or so, assuming the vendor is still around) you'll need to buy upgrades, because you can't get support for the old stuff at any price.
OTOH, you get gigabytes of applications bundled with a typical Linux distro. There are other apps and support information out on the Internet at very competitive prices (most for $0) if you want to dedicate a fraction of a headcount for self-support. If you go with RedHat you can also buy commercial support.
As you scale up, your per-seat licence costs increase. You'll probably have to dedicate a portion of a headcount to keep track of all your licenses (or let BSA do it for you, at a substantial cost).
You may find some situations where the OSS alternative is the more expensive route. If you have specialized hardware, for example, you might have to pay someone to write some drivers. Every situation is different, but in the majority of cases, going with closed-source is more expensive in terms of money, risk and long-term stability.
The absense of real numbers to support TCO assertions might indicate that there aren't any. MS is studying this very hard; perhaps they'll pay Gartner or somebody for a reasonably believable "white paper" soon.