DMZ and ICF confusion w/ iis 6

I an article (www.devx.com/webdev/article/17085/1954?pf=true ) I read that
the preferable way to configure a DMZ is:

1. Configure a "back to back" DMZ where you have an internal & external
firewall server.
2. Then in the article he says to go to local area connection on the server
(which one, there are 2 now?) and select 'Protect my computer & network by
limiting access from the internet'. Then he says to go to the Services tab
& check on the protocols that I require, uncheck the ones I don't.

I'm confused here. Why 2 computers, in #1. (At my company currently, we
just have 1 dmz server, and do some NAT'ing thing where we hide the true IP
address from the outside world.)

In #2, is this protocol setting something that you do ONLY if you have ICF,
and not if we have a checkpoint firewall or some other 3rd party firewall.

TY Jason Shohet