lol.. my school has that also. All you gotta do, is disable the proxy server.. and if it has protection, like something that blocks out keywords and crap..

all you need to do is; control + alt + delete, end task it, and veali!

for the proxy, you have to get rid of the protection, first.. if there is, but.. if there isn't.
just go into the internet explorer> tools> internet options.. then, connections get rid of proxy ****.. and bam!

more help is at my site

quick link