what you are doing is not common. the best way to set up internet sharing is buy a router with built in switch, most routers come with this standard. this provides protection on the internet (NAT) and usually they provide up to 4 ports to connect computers to the network.
okay, maybe i could explain that easier, lets say this: get a router, plug your broadband internet into the WAN port, and plug each computer to the device ports on the router's built in switch. CAT5 is most commonly used and network speeds are typically 100Mbps.
a less common way to do this is through ICS type sharing. one computer must be always on that acts as a internet sharing server. you would use one network card that plugs straight into your cable/ dsl modem and the second network card plugs into another computer which is sharing the internet connection
you can use a hub with ICS to share your internet among multiple computers. the second network card would plug to the hub and all other computers plug into the hub. sygate home or office network is a good software for ICS. realistically ICS is only good if you want to aggregate 2 internet connections together to form one fat pipe.
