Here's a more detailed page from Henrico school:
http://www.henrico.k12.va.us/Announcements/Dell/
No doubt they will try to do prevent software installation and control what the children do with the machines, but I would be surprised if took more than an afternoon for at least one enterprising child to have a different operating system booted. In particular, from the web, the machine has at least two USB ports which might well mean that someone could get the Puppy distribution booted off of a USB port, maybe within a few minutes.
What caught my eye was the big upfront difference: Apple quoted $4 million more. $4 million can pay for a number of FTEs. Also, it appears that Office wasn't part of the Apple quote, although that's what Henrico schools wanted according to the article. (Although it wasn't clearly stated that Dell had included Office as part of its quote, it seemed to imply that.)
M/S Office?! Great! The kids can worry about fonts and styles over silly old-fashioned things like grammer.