Any good proxies to bypass school blocks?

its windows 2003 server that they run on, and i login using the winXP local login. listen up, my school has a tight policy with the computers and and if i'm caught doing anything even remotely threatening i could lose my privilages for the rest of the year, plus possible suspension/expulsion. there's gotta be a way around that crap. how do i tell if they can log/are logging that kind of stuff? (websites visited, bad logon attempts) are there any default user accounts that i can try to log on that have high access rights?

Administrator, which requires a password to log in (or you can go into safe mode and attempt an Administrator login from there), that works - unless they disabled Administrator entirely.

You do need some rights to change settings and such, and I wouldn't recommend installing a keylogger or anything because it's probably being scanned remotely (and you might just get a teacher's login - they have almost no rights whatsoever in a normal enviroment, because they would just screw things up.)