You will need a router/hub/switch for this using straight thru cables, or you can save some $$ and use a cross over cable, and just network them computer to computer, instead of computer-switch-computer.
Scenario 1:
1. On computer A, On your dialup connection properties, enable sharing of the connection
2. Computer A connects through dialup to internet
3. Computer A wired to a switch through network card
4. Set computer A's TCP/IP address to 192.168.0.1
5. Computer B connects to the switch with it's network card, make sure it is set to obtain an IP automatically
6. Computer B should now connect through computer A, to the internet.
Scenario 2:
1. On computer A, On your dialup connection properties, enable sharing of the connection
2. Set computer A's TCP/IP address to 192.168.0.1
3. Connect Computer A and Computer B via cross over cat-5 cable
4. Make sure Computer B automatically obtains IP Adresss, and then it should now connect through computer A, to the internet.