In these days of (stories of) obese students, classroom thuggery and global warming comes a story of good news on all fronts:

http://www.itpro.co.uk/news/184326/york-school-virtualises-desktops.html

This seems to be an ideal solution. Talking to teachers about IT I always hear stories of support and administration nightmares and talking to kids about IT in schools I hear of slow boots, crashes, sneaky ways of getting to play games & competitions to see who can make the machine most unbootable. Thin clients should make the support and admin easier (once the initial learning curve is mounted), be less nickable, cheaper to install & gloriously quiet & fast to boot to boot (do you see what I did there?).

One extra thing I would sugest is to use optical mice - teachers who have glued the mice shut to stop kids nicking the balls tend to find them hard to clean!