You CAN download msn in school.. Just look for it in japanese or something and hope you will get lucky. But It doesnt really matter because your filter wont allow it. The only one that is allowed, without using a proxy, is AOL.. Don't ask my why.. i'm guessing people never tried it. That or trillian.. I just downloaded and installed a bunch of things on my ipod last year and I couldn't get trillian to work right and aol is tho only otherone that worked.
You won't be able to install it on the school computer. Not being an administrator will allow you to download things but not install them.
I haven't found a proxy that works at school yet, except ijapan/red, but I click on United States and type in hotmail.com or myspace or whatever and it just says "page cannot be displayed" .. So I'm going to make my own
but I have no idea what I'm doing.