The mixed environment that runs across our planet is something that UNIX is right at home with. All mail and other protocols, too, are what UNIX systems have evolved and adopted over the decades. Windows runs on a single platform, on chips from virtually one vendor. With NT, they're expensive extras. The UNIX server is manageable from anywhere with a simple telnet.
Stability remains the big issue.
Very few things that you can do will crash a UNIX server. But I suspect Microsoft has tried to take on UNIX too early. Moreover, I believe that much of the industry and some of the user community wrote off UNIX too early. For over a decade, India has been UNIX country, starting with the extensive banking computerization, then our stock exchanges, and many other large and critical applications. All in all, you're likely to see a lot more than you'd expect of UNIX in the corporate workplace.