Wow!! Nice discussion. Let me through my 2 cents worth in.

Why do you think a home user should work behind a firewall if closing ports and disabling services preforms the exact same functions?
This was the original question. My answer is your average user doesn't know what the heck a port or service is. Thats a bad assumption that most of the experienced folks make. The average user doesn't know what they need or when they need it. This is the very reason why M$ is an empire. Their marketing people understood this about the average group of people who would potentially use a computer and understood how vulnerable they are.

So the linksys and netgear's of the world are making a mark in the home networking market selling SOHO equipment at reasonable prices. They should thank M$ for this.

How many of you guys remember the green screens, the Wyse 50 terminals, the amber screens? Didn't have to worry about your terminal being infected did ya?

With M$ being so widely used and also having an OS that is the most likely to be exploited, firewalls nowadays MUST.