These are students being taught for their future and will need the skills required for their future jobs. Pushing the Mac platform is a horrible idea and a form of playing russian roulette with their computer skills and future job possibilities.
Keeping in mind what is possible through *freely available* VMs, and the programs that are available on any platform, if the skillset that you gain in high school computer usage is so specific that you *need* a windows machine to do your work, because it probably means that you need Windows 7, and won't even be flexible enough to handle Windows 8.
Regardless of anyones personal opinion of computer OS's, Windows still rules in both the personal and business OS level. And I don't care what anyone else has to say on the level of 'but, but, Macs are slowly gaining.' Thats great for Mac. But here's a good dose of reality. OSX was released in March of 2001. Its now June of 2010, just over 9 years later. Mac has been able to improve its market share from 1-2% to 6-9%. That means less then one in 10 computers is a Mac even after 9 years and one hell of an aggressive marketing campaign (we've all seen those 'Pc vs Mac' commercials).
None of this stuff matters. I can go sit down at a Mac, PC, linux box, whatever. Tell me how to get to the word processor. Tell me how to get to the software that I use the most.
The school is also mentioning security as an issue, but thats getting more and more of a questionable problem. Fact of the matter is, Windows 7 is pretty secure (but not the most secure). And computer security is no longer as simple as how fast a virus/worm can spread. This keeps being shown on the Pwn2Own contests, as security is now based on what else is running on the computer. The biggest security risk seems to be running Flash on the system.
Do you think, from an administrative level, that it's ever been about that? That's just a symptom of the problem. The biggest security risk is stupid users, and nothing you do can stop them from getting their computers infected with something. The cure is having separation of security concerns to limit the damage, and it's still more of a (only a) problem for Windows than it is for anything else. If I was a computer administrator that had to support 1600 laptops that I didn't actually have control over, I would want something to make it easy to fix them and isolate problems.
Also to consider is things like hardware compatibility. Most hardware is written to support Windows, with some to little to no support for Mac. Sure, Macs play great with other Mac hardware but if Apple doesn't make it things get iffy (again, depends on what it is your talking about exactly). These students go home and will want to use their laptops with their devices at home. Have a blackberry phone? Good luck doing anything but the basics of syncing (and no, showing me some complex set of instructions doesn't count. We are talking students of different interests and backgrounds, not the slashdot crowd). Printers and scanners?
From the perspective of the school, though, the things that they're going to worry about are the things that everybody has and that teachers are actively told to encourage the use of. And it's a lot easier to support 1600 identical machines than it is a huge number of completely different kind of machines.
I completely agree with you here. These are students being taught for their future and will need the skills required for their future jobs. Pushing the Mac platform is a horrible idea and a form of playing russian roulette with their computer skills and future job possibilities.
In summary: the premise that a particular piece of software is necessary to gain an understanding of how computers, technology, or anything that one would learn in high school is ridiculous. Of course, if I ever have children, I'm sure that mine will be unbelievably competitive compared to yours if you teach 'em that full mastery of how to navigate windows and use office products will take them somewhere in life while I'm teaching them the underlying concepts that govern how all computers work. ;)