Unix makes you struggle with a server environment that's more complex than ever
Okay, now anyone who's ever used a Windows server environment and a Unix environment is probably thinking 'but no, those are the things wrong with Windows, not Unix!'
In short retort:
Unix flavors run my TiVo, my Powerbook, Google.com, and this web site. That's pretty flexible to me. NT Webservers in places I've worked have to be completely rebuilt on a regular schedule to address 'creep' problems that will otherwise bring the machine to a crawl, if not a blue screen of death.
Unix requires you to know what you're doing, or to use tools created by other people. You can always hire an expert, but you're more likely to find a good one for less money than someone who's still trying to pay off their credit cards from the 6 months or more they took off work to get their Microsoft Certification credential. An MCSD credential means you can make bank consulting, and naturally Microsoft pushes employers to use only Microsoft Certified Engineers, so Microsoft's accusing Unix of requiring expensive professionals is a bit of hypocrisy.
Finally, the Windows server environment is quite complex, nowhere near as modular as Unix systems, and gets more complex with each version. Also, since it's a single-vendor solution, if you don't like the way a product's development is headed, it's tough luck, or you can change systems entirely. Unix has flavors, and as they evolve, you can easily port from one to another that better suits your needs (from Solaris to Linux, for example).
It's all about the fear, uncertainty, and doubt, and Microsoft's firm belief that the decision makers in a company are the ones in air so rarified as to know little enough about technology to be brought in to Microsoft's folds by this bunch of crap.