I have thought this would occur for some time, although the move to Max OSX surprises me. I work with the IT needs of businesses daily, and I get two big reasons not to switch to Vista: either the IT pro is afraid of it, or the company see's no reason to change. Same applies to MS Office 03: it did everything a company wanted, why spend money to change it?
Of course there is the security issue with Windows, but that's why I have always thought Linux based systems would take over from Microsoft in the Business world. For one, when you use a Linux kernel, you can have your IT team (and most major companies have a programmer or two) can tailor the OS to your needs. They can add in an Office Suite (not many people can tell the difference between Open Office 3.0 and MS Office 2003, and it even works with multiple document formats including the MS Office formats). Then you may need to code in support for accounting software. That's it.
The great of the Linux system is that once you have the few programs you need programmed in, and the support to upgrade some web-browsing software (lets say Adobe Products and updates for your web browser), you can go about closing off Security problems you find that you couldn't close with Microsoft Operating Systems because Microsoft is a licensed product and changing the code is a breach of contract. Could it take a few months, maybe a year, to code this OS and its functions? Sure, but then once you get the OS you wanted/needed, you never need to change it (sans, again, updating Adobe products or such). The costs then of an OS like this are incredibly low, and the nature of something so simple and without all the "back-doors" (as they are known to Windows Operating Systems) you are more secure as well.
But if you stick with the Microsoft Operatin System, you have to live by there rules. Paying over and over again for new Operating Systems you didn't need (because Microsoft will drop the support for their old system, and the only way to keep it secured is to get their updates), more Office Software that you didn't need to buy AGAIN, and on and on.
I've been experimenting with what's been called the "Standardized Business Platform." It's a basic Linux OS (seems like the best parts of Red Hat and SUSE), Open Office, and VLC Media Player. It does everything that your cubicle people might need to do. There is a space in the OS that allows for the installation of Peachtree Accounting Software, and another distribution of it has graphics editing tools. So there is a version for Accounting, Marketing, and then all other departments. And its free: the only issue becomes networking and driver support, which are existing issues for most large and medium businesses that already have IT teams to deal with such issues.
And the best part? Once it's installed, its completed closed off to new programs. A virus couldn't run its own dedicated process because the OS has a set list of processes it can run: if the process isn't on the list, it won't start. I downloaded a few of the "XP Antivirus" distributions, they would actually find their way into the file system but the moment they started to run any scripts, any code at all, it just shut off. The only way then to get a virus on the machine is to piggyback it to the programs on the machine, which means all your IT has to worry about is closing loopholes around the program operation, a vast improvement over Windows OS's.
The best part is it's free. The worst part is that it doesn't eliminate your IT department. But really, you need your IT department for a Window's OS, so this just eliminates the need for additional licensing.
Oh one other caveat: it tends to work best on pre-built systems, as it has some driver support built into the OS. Which means, if you are a business, you'd have to buy your computers instead of building them, or if you are a large corporation that DIY's it, you need to pay attention to components used. (that last paragraph, if you can't tell, is riddled with sarcasm)