Why I don’t have an antivirus or firewall
Companies like Norton and McAfee charge a hell lot of money for software that makes sure your computer is unstable, without performance, ruins your experience whenever you are trying a new application or just blocks you out the moment you try to uninstall it. These companies have the nerve of naming things w32.evilthing.worm or something while their own piece of junk is probably more harmful then the things they attempt to remove.
Let's face it, the software the average computer user buys to "protect" his/her computer is way too primitive and resource demanding. They are known to be full of bugs, extremely easy to hide from as a piece of malware, and best of all: you can't control shit about them (Norton has maybe twenty configuration options, try making it to not start up when Windows does).
But there are more reasons I don't have their junk products: I just don't need it. When I receive a mail from this beautiful Polish lady that would love to chat with me, through her very own chat client, which is of course included as chat.exe, I realise she is just not right for me. Or when someone advices me to go back to Internet Explorer 4 because it has more advanced features, I might question that persons intelligence (for two reasons: recommending Internet Explorer and recommending an older version).
After that, there are still two methods on not getting annoyed by malware or attacks. A good method I use is just misconfiguring your router in such a way it doesn't accept any reverse connections but HTTP and some other protocols. The second method is the one I'd recommend to everyone: try not to make too much enemies, because not all virus mails you get are unsolicited spam mails...

You are right. When I was running on Windows I didn’t receive a single virus in 5 months without anti-spyware and anti-virus programs. I use my brains as a virus scanner.