Floppyfw does Routing,Firewall and dhcp
i added a package that logs in as well specially made for Telia swedens
ADSL log in.

The setup is easy get two 3com cards, 10mbt is enough
I use ISA 3com, 3com because linux has such an easy time
with them and cheap for used ones

a floppy drive (no HDD needed)
KBRD and Monitor just needed a first

I liked one called JT that I found in one of their links

Just read the howtoes on their page

It is good to have the 3com software so you can boot with

MS floppy and set them to different IRQs and ports
if you look at the 3com cards it sais ethernet address
somewhere the lowest number (in hex) becomes
eth0 the one to hook to your
ADSL modem (or other)
eth1 connects to switch/hub or single puter

in MSIE and network just set it to get IP automaticly
and you are ready to go.

You might have to try some different distroes
to fit your stuff the best

just download a few images and make floppies to try
there is a config file on the floppy you can change
from w9x with write (note pad messes with carrige returns (CR)
you need to change to static IP if that is what you have
default is dynamic

and depending on your supplier it can be enough
to put username and pass in config to log in ( I needed extra package)
otherwise you just log in from your surfing puter

well it is all fairly easy it helps to know linux but no need (I don't)
just read HOWTOes