No, everybody knows that exactly the opposite is true. Just install Windows 7 64-Bit on your precious Intel Mac and you will see immediately just how much faster Windows is -- and how much better it handles multi-tasking and multi-processing than OS X. (You could also run good old Windows XP or even 64-Bit Vista to get the same result.)
One of the main reason for the better performance of the Microsoft OS is the Mach kernel architecture used in OS X - it requires too much communication overhead. NT originally also used a Mach kernel design, but Microsoft successively dropped it for performance reasons.
Also, Windows has much better memory management than OS X. And to add insult to injury, it is also a much better optimized 64-Bit operating system.
The performance difference between the two platforms was even worse for Apple when Macs still used PowerPC CPUs -- those sluggish beasts didn't stand a chance against the Intel CPUs. Guess why Apple dropped them.
In terms of stability and robustness, Windows NT-based systems blow OS X out of the water without even thinking about it. I still see the rotating beach ball in OS X quite often. But I have forgotten what a blue screen looks like.
Now with Windows 7 around, Microsoft also gives OS X a run for the money when we're talking about usability.
And when you need an enterprise-ready platform, only one of the two is going to cut it. And it's not OS X.
Well, since you obviously haven't read the news in the last seven years: Windows Vista -is- a complete re-write, and Windows 7 is the optimized version of that re-written Windows. And old code-bases tend to contain tons of unnecessary legacy code - and Linux and Unix are included in that statement. But for the sake of compatibility, people --WANT-- and even --NEED-- that bloat in a platform. No big company wants to spend a couple of million dollars on re-writing their own software just because fancy Uncle Steve Jobs decided to drop some features just to push his hardware sales. That's why you don't find Macs in corporate environments, but tons of PCs with Microsoft software on them.