You might find outside America schools are using PCs built in their own country. All the schools I've worked at in Japan use NEC, and all reasonably new as well. Except for in the staff rooms; they usually get the old ones (even saw a few running Windows 3.1). Still, it's the American market that everyone is after.

Selling to schools is a good bet for educational software. The schools themselves will buy a heap of licenses at a time using government money, and will effectivly make parents aware of your software for a few more potential sales.

Generally though, most schools aren't using their computers effectively. At all the schools I've worked at (I worked at quite a few as a dispatch teacher) computer time was time to play solitaire, net games, and play around with graphics programs. So you also have to find a way to market to administrators and teachers who don't have a clue.