A recent Free Software Magazine article points out that using Linux protects you from potential governmental spying or hacking in two ways. First, Linux is open-source, so it would be extremely hard to inject a backdoor in to its code. Second, since Linux is far less commonly used than, say, Windows, a governmental organization is far less likely to target it. All of this logic basically also applies to ordenary hackers, too. (And if you don't think that governmental hacking will be an issue, it will almost undoubtable be an issue in some major country in the next few years.)