Depends on what you want to do.
NT is great from a price perspective when compared to Solaris, but does not compare to Linux (free - which nothing can really beat).
Solaris is great as long as you run it on Sun hardware (can be very expensive).
I believe Mindcraft showed that IIS was supposed to be a faster server www than Apache on Linux. It happened a long time ago, but basically Linux was beaten. With the advent of 2.4, I doubt this will be true any longer. Of course, you take the speed away, and you are left with a www server with less features and more security holes. I cannot tell you how many security bulletins I receive from Microsoft in regards to IIS.
NT really wins in many ways because of the huge amounts of hardware that has come out with drivers for NT.
I believe Samba on Linux has more features than SMB on Windows / NT. So, beaten again in a sense.
From a client perspective, I would have to go with Windows all the way, though. It's interface is slicker, more polished and easier to use than KDE, Gnome, Enlightenment - whatever. IE is also one of the best browsers around and only runs on Windows and Macs. Also, Solaris and Linux lack the games (very important to the consumer market) and software that Windows has to offer.
I believe that Linux, Solaris and other UNIX variants really excel at being servers of some kind while Windows has proven itself as a good client.
Complain all you want about Windows, but at least it doesn't have a lame smiley face for it's boot up screen.