At the risk of sounding trollish, I'd like to point that the "for obvious reasons" in your question sounds funny for some people and scary for another people. A potential reader of your question would almost certainly replace this "for obvious reasons" with some of his hidden fears or assumptions that are not backed up by any facts. For example "this can be an alien"/"this can be a spy"/"this can be a terrorist"/"this can be a pedophile"/[insert your favorite here]. That potential reader instantly doesn't trust you anymore and you'll miss a chance to get an answer from him.
But this is psychology. Let's go back to the technical part.
Bruce Schneier, a security guru, said: "Security is a process". These are not just some wise words that sound cool and make you look smarter when you say them to other people. This is an important general criterion that you shall apply to any situation involving security.
So let's talk about your situation. Let's say you have a fully encrypted hard drive and you use a strong encryption key. Are you safe? It depends. Because this is a static situation. And a process is continuous, not static. Does your computer connect to the internet? If so, you've got a lot of new factors to consider. You have personal mail stored on your encrypted hard drive? Yes? Ok. It is relatively safe there. You've got it via pop3/imap from a server and you didn't use an encrypted connection? Well, here you fail. Somebody could have been sniffed it and doesn't need to break into your encrypted hard drive. You used SSL when downloading mail, but the mail server doesn't use an encrypted storage for storing mail? Well, theoretically you have problems again. Because the mail server is the weakest point now and a potential attacker will try to go for it instead of going for your encrypted hard drive if he wants to get at you.