Paddy:
There are more than two platforms to consider, I think. What about UNIX and its many variants, for example?
I think it would be unwise (irresponsible, in fact) for a school district to commit to using just one platform. Competition among vendors most always benefits the consumer. When comparing prices of Wintel vs. Apple solutions, be sure to look beyond the initial hardware costs and consider also the long term software licencing costs. Maintaining Microsoft licenses can be a considerable burden over time. There can be other hidden costs associated with choosing a Microsoft solution as well. Virus protection is a requisite when deploying Window computers.
As far as networking, in a properly designed network the choice of operating system should be largely irrelevant. Even more so in the future, as open standards such as XML continue to gain acceptance.
I work for a municipality and use a Mac to do much of my work. My choice of operating system is entirely personal, but I must say people's jaws drop when they see me remotely administering the Police Department's Windows-based servers through a secure VPN tunnel from the comfort of my office, using a Mac. And the Mac's underlying UNIX-based OS gives me great flexibility in accomplishing my other day-to-day tasks.
Your school district should base its choices on what represents the best monetary value, and not be swayed by sales presentations from any particular vendor. They would do well to examine what other districts are doing, not just locally but from farther afield. From that, they can work out what the "best practices" appear to be.
