I'm actually mildly surprised to hear that your school had a 40Mbps connection. My school had around 2000Mbps shared between 5 dedicated computer suites and 4 mobile laptop suites. It had 2 servers to manage everything too, which turned out not to be the best designed system because many of the programs we needed to work with never worked correctly if located on the servers and not on the local drives themselves.
Even with around a hundred kids at any one point downloading all sorts of content using Kazaa, WinMX, eDonkey, etc, I never saw less than 20Mbps for my own downloads (which typically had less to do with games/porn and more to do with random curiosities). Sometimes, when I ran a speed test, I would get around 1200Mbps.
I was also the type of person who persistently surfed the intranet searching each computer one by one for the inevitable "Download" folders and systematically deleted them. I heard more than one accounts of people complaining about lost work, but when I actually showed the teachers what I was doing, only the system administrator could really uphold the complaints... they may be breaking the rules with all their illegal games and porn, but so am I by surfing the intranet when there's supposed to be layers of protection against it (case in point, I discovered one day a file on one of the administrator's accounts that had a list of everybody's user names and passwords - I warned him about that a couple weeks later, but also said that I didn't plan to use it anyway... except for when people stupidly lock the computer so others can't use it once they leave).