I don't think you should be able to do WHATEVER you want--whatever in a reasonable fashion, however, is different. As long as you respect a computer, it will show equal respect for you. I respect even my computer at school, and thus I never have problems with it. If everyone showed this kind of disposition, we'd have no problems (don't get me wrong, I have no delusions that this would or should be so). But the thing is--lots of people who use computers to their own ends know what they're doing. They know how to keep it nice and neat and not destroy the computer in question in the process. You shouldn't be persecuting them for taking certain liberties with their privileges, if they leave a clean trail.
But you see, my school's idiotic. They won't let you use alternative browsers, and at the same time, won't let you disable IE activex, effectively forcing you to pollute their computers with crap. Try showing them this, and what do they do? They deny it.
I'm not going to deny my school's lab has rules and I should follow them--but they're really subjective. The teachers are the ones who TRULY make the rules and enforce them. For instance--I'm organizing a quake LAN party to be played every Friday when we get time to play games--and my teacher's perfectly fine with that. What do you think the administrators would think? "OMG HACKERZ"
Yeah, sometimes the rules shouldn't be followed. Sometimes.