OS on a pendrive - if I took one travelling, if I used an internet cafe computer to boot the OS, would I be able to use the internet?

I'm going to be travelling for a long time, and only have access to quite dodgy computers. Obviously, I don't want to do banking on a computer that could have a keylogger.

I know you can install OSs on a pen-drive, so would it just be as simple sticking it in, booting it up, and getting on the net? The places I'll be using won't have any of that cyber-cafe timer software or anything.

I already have an encrypted pendrive, but that doesn't help when I need to unencrypt it on a dodgy computer.

Does reddit have any suggestions for an appropriate OS if this is possible?