Over the last few years, computer security has finally become a discussion for more than just system administrators. These days one of the main concerns, understandably, is the security of data once it's left your machine. Once the data is out of your hands, it seems to be uncommonly easy to intercept.
Encryption goes a long way to prevent "across the air" surveillance, but there’s also a mentality in the computer security world: If someone has physical access to your machine, nothing can stop them.
When at home, most of these concerns can be managed.