ethernet

Hi have an ? about two ethernet cards as i just got the other day an cable modem setup here and now the ethernet card in that machine is use for the cable modem so i guess i need to add another card to that machine so it can talk to the other card in the other box so the second card in this box will be eth1 if i am right and the one card in the other box eth0 so am i right when i say the routing will be the same just that the one from eth0 will now point to eth1 instaed of the eth0 it use to be before it became in use by the cable modem am i right in my thinking before i go and try this thanks in advance Bob