Re: Thin clients
I would be strongly inclined to follow Lars Noodén's recommendations.
You could use Linux to install Windows images as either a thin client or a thick client, but you run into issues.
Chances are every PC you're dealing with uses an OEM Windows image. Those images are generally limited to install on very few PCs. One time we tried to get new images from the manufacturer, and they said their images were limited to 50 boxes before they changed a serial number. So any image CD from this manufacturer would only install onto 50 distinct pieces of hardware. Number 51, even if the hardware were otherwise identical, has a different identifier built into it and needs a different CD. I'm sure every manufacturer has different specs regarding that but I doubt there's a manufacturer who just lets one CD install onto any of its products.
If your school is like every other place that uses computers, you didn't buy them all at the same time. You bought them 10 at a time or even less, and from whoever had the best price at the time.
So in order to do this with Windows, you'll need to buy appropriate licenses for however many copies of Windows, not an OEM variety but a full version. Even if you get a site license of some sort, that's gonna be a significant cash outlay that I doubt your bean counters will like.
There are specific licenses for Windows and this sort of scenario, and you'll probably need to get that. There's a Microsoft number you can call to get an idea, they're very helpful and since they don't actually sell the licenses you can ask them all sorts of crazy questions and they'll probably be much more helpful than you imagine. They know that if you're calling them, you're TRYING to be legal, which makes you one of the good guys as far as they're concerned. If they don't know, then they don't know.
All that said, and having jumped through some of those Windows hoops, I recommend starting with 10 boxes you get from your school (or maybe a classroom), install one of the scenarios Lars gave and show your school a pilot of what you intend.
Help stamp out MBR partition tables. Use GPT instead!