One thing to consider is that, depending on the school, the network admins may not be happy with you sharing the connection via open wifi - if you setup security on the second connection (or use the bluetooth, which is secured by default, I believe) they have less reason to care - they may not notice/care anyway... The other thing to worry about (again, with the open wifi suggestion only) is someone else using your connection will appear to be you - and can then download questionable content on your username...