Well, that goes back to my original statement. As an IT administrator, I don't want people doing things on work computers that are not work related. Time wasted every year by employees doing non-work related things costs companies millions of dollars.
Having said that, it's a little different in a school like ours because the whole idea for having a computer is to learn more about it. I don't lock down anything on our computers as far as what you can do with it. In other words, if you as a staff member want to install software like iTunes or Real Player I don't have a problem with that. Our lab machines are locked down with DeepFreeze so when you reboot them, they return to the default state my department puts on them.
If I were the IT admin for a corporation you wouldn't be doing anything personal on them at all. Dow Corning fired a whole bunch of people within the last couple of years for non-work emails. They have the right to do that, it's in their policies. A friend of mine works for a health department and they track all computer usage to make sure people are doing their work instead of wasting time on the 'net.
Anyway, the bottom line is that unless you have admin rights you can't install anything.