Serving a web site

I am interested in hosting a web site. I want
an internal network based on RFC 1918 that
interacts through a firewall ( ISA 2004 preferably) to an external network that is
exposed to the network. I have many questions.
First, what should be the components of my
external network. Would I require a DC there
running IIS 5.0. And where would my c:\interpub\wwwroot be located, in my internal
network on on the external network. This is the
directory where my ASP, html etc. pages are located that have to be transmitted across the
internet. Any comments here to help with some
ideas?