Re:Fiber (and other suggestions) (Score 2, Informative)

I can't remember but if this was ever true, but it isn't now.

Extreme Networks and Cisco both have long haul GBICs available, and have done for a little while.

I don't have info on the Cisco models available right now (Ciscos website is BIG!), but Extreme have a 1000BaseLX-70, that will do 70 km on singlemode dark fibre. On top if this they do what I could best call a gigabit fibre line driver in the form of a "SummitGbX"[tm]. They claim it will definately do 80 km, and possibly up to 100 km, I have heard one claim that these units managed to reach 120 km. Basically, you hook these up to your 1000BaseSX interfaces at each end, and it does some wibbly-bits to bridge the 80 km or whatever length of fibre :)

I would love to verify all this independently :) but I never even dared ask the prices :/

Of course, all this doesn't really help your cause much... you might be able to find a friendly telco that will blow fibre in for you. Apart from that, your realistic options might not include wireless.
At that range, you will have to go for some sort of microwave transmission, and even then you will probably have problems due to the Fresnel effect, which bends and scatters photons at the earths surface. The maths escapes me at this moment, but to reach 45 miles in one hop you would probably need to have each end nearly 200 foot up in the air in order to clear inconvenient obstacles in between, like buildings and trees (how careless to put them there!). To do it in several smaller hops might be easier, but then you have to rent or buy locations to put your repeater stations on.
Another possible thing to do would be to link all the schools locally to a central point using some easily available method. Microwave links might be suitable here, as well as optical wireless links, T1 leased lines, or whatever you chose. The most usefull central point would be a telco CO, which means that you will only have to rent backhaul bandwidth on the telco's network without having to pay for an expensive tail to anywhere else. Almost all CO's will be served by fibre now, which makes renting a fast connection very much cheaper and easier to provision. As you well know, it is that last mile that makes it expensive.

I wish you good luck :) maybe you'll let us know how it turns out?

btw, I don't have any connection with Cisco or Extreme, I just use their kit in my job