Good for you.
As for me, I don't really think that security should be a big concern. On this computer I only have a blockland client and a little C++ project I've been working on. I don't think anyone is going to steal a text adventure game.
you wouldn't know if they'd stolen your entire digital identity, your real identity (if you use facebook) and hunted you down
if you aren't taking steps to make sure someone doesn't have it, you should assume someone has it. are you comfortable with someone having access to all the accounts you access on this device?
plus, you should also consider being a role model for other people. by being knowledgeable about these kinds of things, you can help other people who really need it