Case #1:

Network scenario and constraints:

Small business and small network, in fact a real IP network consisting
only of one system in terms of Internet addressing.  The business has
one machine (a router) with one "real" ip address hooked up to a local
ISP.  There is one internal ethernet network that does not have real IP
addresses.  The real IP address is 200.1.2.3/24.  The business has a
relatively cheap telco circuit, a DNS name (foo.com), and no IP network
address.  They can be viewed as having a leased-line (not
on-demand/shared dialup for the circuit).

The ISP access mechanism is a relatively cheap WAN access mechanism
(say ISDN or worse ... a 28.8k baud modem). The internal network has 5
hosts that all have Windows NT client on them.  Note that the ISP
charges more money for an internal network #, and real routing
internally; i.e., real routing doesn't exist and the customer doesn't
want to pay for it.  You *only* get one real IP address.  Assume
however that the business wants internal machines to have some network
access; e.g., email.  (Note: this situation applies to most homes
at the moment that have more than one computer internally).

Picture:

				|
				| wan circuit 
				|
			      _____  the real IP address
			      |   |  the only real IP node (assume router)
			      -----
				|    internal ethernet lan
		--------------------------------
		|	|	|	|	|
		Win NT clients

Solutions:  What can you tell the business customer about how
they might setup their network given the above constraints?
What possibly configurations or setups can the business use?