Schools are well known to block p2p file sharing programs. Try asking around and see if anyone else is able to connect. You may be able to connect to other computers on campus. Best bet is probably just to ask someone in administration.
You could try changing ports. See Aaron's advice in this thread:
http://www.gnutellaforums.com/showth...69&#post250969
Or you could try setting a proxy:
http://www.gnutellaforums.com/showpo...3&postcount=11