I put a dummy address into my address books like #email@example.com. If a worm sends a email out to my entire list I should get an undeliverable message.
I don't know if it works as I've never caught a worm that does that.
Passwords with numbers, case changes and symbols are something like 9,000,000 times harder to crack.
Keep you anti virus and internet security software up to date. It's something I personally don't mind paying for.