Michael, I am sorry this happened to you, but it isn't really about hackers or the Internet. This sort of information is readily available absent anything to do with your desktop or level of computer security. Think how many times you are asked to give out your social security number for example. Or how many times the waiter sees your credit card information. There are any number of ways this sort of thing can happen. Just try to be smart, and at the same time use appropriate technology.