Well, if you're sharing a modem connection to the Internet, you don't need two network cards. If you're sharing a high-speed cable or DSL connection, you probably do. (Can't say I've tried it.) One network card is used to connect your two machines and the other goes between the primary machine and the cable or DSL modem. ICS is the way to do that in either case. (Not the way I'd do it mind you, but the way with what you have on hand.)