My internet is provided by a 3g modem usb. I am sharing the internet connection through my desktop into a router and then to the rest of my Ubunut machines. Currently if I want to file share I have to go into the network manager and change the eth0 settings from shared to dchp automatic and then unplug the cable from the internet port on the router to one of the network ports. Is it possible to add another network card to the main machine and use that exclusively for either internet or file sharing.

Long time windows user, Ubuntu 10.10 rocks