Re: Public School WiFi
I've heard that AVG is good but I personally recommend Comodo... it's really a hands on program though as you get prompted for access to just about any program that wants to use system resources. However, it's good to know when something/someone is attempting to access something it/they shouldn't be.
The main concern though that you're referencing is packet sniffing. On a public network, you will encounter people that use programs like WireShark. They sniff out packets and can steal data right out of the air...literally. The use of passwords/etc on a public network is generally inadvisable. Anything to do with your personal Identification can always wait until you're on a secured network or physically plugged into a connection.
Humans are the only creatures that won't live up to the their potential. Give everything your all. When you die, die on E.
So I ask you, what do you intend to do now?