Why aren't schools adopting open source?

I've often wondered this same thing, myself.

http://blogs.techrepublic.com.com/opensource/?p=811

Adoption = savings, freedom, updates
Here in Kentucky the public schools are seriously strapped for cash - to the point that arts, humanities, and teachers (a precious commodity) are being dropped to save money. I have a suggestion for the public school systems around the country - adopt open source software and you will save a lot of money. Not only will you save a lot of money, you will also be able to keep all of your software up to date.

This would not be the case if the schools adopted open source software. No longer would schools be using out of date and unsupported operating systems (I know schools and institutions still using Window 98 because they can’t afford to upgrade). Every school would have the latest-greatest software and the students would be somewhat closer to the cutting edge.

If adopting open source software would allow schools to save thousands upon thousands of dollars per year (per school) I have to ask, again:
Why are schools across the country not migrating to open source software so they can focus the dollars spent on software in such a way to further the education of our children?

Educational institutions are supposed to be a pillar of learning and intellegent decisions. But it seems, as far as software is concerned, our educational system is consistently making some farily unintelligent choices.