PCs Sharing ADSL Connection? (Part 3)

* Support sharing of an SBC ADSL connection. Our
SBC connection uses dynamic IP addresses. I want
to share this connection among the PCs without
having to change any aspect of my "provision" from
SBC.

* I want email to be routed to it's respective PC.
I have the impression that this is a fairly standard
capability.

* I would like whatever firewall/security capability
that is appropriate for our home network. This is one
part of the networking world about which I am pretty
ignorant.

* I want to pay the lowest "going rate"--but I don't
want to be "penny wise and pound foolish". Can you
recommend a good place for me to do this shopping?

---See Part 4---