I have had some experience with wiring schools. Your mileage may vary depending upon where you are and the attitude of the local administrators and school board but it might be good to get at least the principal/other teachers on your side before expanding too far.
In my one experience with this a nice grassroots effort like this, initiated by a teacher, died an ugly death when the school board stopped it. Basically they and the school district admins refused to let anything happen until they were convinced that noone could ever do anything "bad" online. Here Bad was a largely undefined quantity. Unfortunately this stoppage meant that the system that had been installed on volunteer time sat unused for fear that it might be. So far as I can tell the problem with this initiative was that they sought permission rather than forgiveness and had no demonstrated successes of students learning on the system.
Ultimately we got computer updates largely through the efforts of one students' father who, like you, just dove in and helped. He of course had to fight uphill battles with the district but thankfully was aided in that by the school as a whole.
With that in mind I'd say you should get your fiancee to wow the rest of the school particularly the principal with what has been and can be accomplished. Then if the school board comes butting in you'll at least have an ally and demonstrated cases of kids learning and not doing "bad things" with the machines.
On a more practical note you might also clue the school into freely available tutoring systems. Many educational researchers put their work online for free meaning that there are Intelligent Tutoring Systems that your fiancee's class can access online. One such repository is the LeanLab at Carnegie Mellon University: http://www.learnlab.org/
Good Luck.