Assuming your computer has Internet access (e.g., you're connected directly to the modem), then yes. Connect them using a standard ethernet cable (very unlikely you need crossover cables, those have been made obsolete by auto-sensing MDIX ethernet in modern network devices), enable ICS on your Internet connection, and share it w/ the other network. Just make sure both network adapters on that other network connection are set to DHCP before enabling ICS.