2 nics for lan+cable ?

hello,
I have a relatively simple question. I have 2 computers, each has a nic which is connected to the hub then connected to the cable modem. right now I have tcpip installed for internet access. The 2 computers have seperate ips and are working properly. ( except the 2nd computer sometimes seem to lose internet connection for no appearent reason while it never happens to the 1st computer)
Now I would like to know if I can get a LAN setup simply by installing netbui on both computers? or will I need to get 2 more nics just for the lan?
Can a single nic be used for cable internet access and LAN at the same time?

Thank you for your input.

Yes it works just fine