Cable Modem

Currently I have a PC(P166) that has a cable modem installed on it. I have another computer that I would like share the cable modem with. The other computer is equiped with a NIC card. I have a hub as well as CAT 5 cabling. Do I need to purchasea router instead of using the hub. Not really sure how to configure this. I appreciate someones help. Thank you.

Markus R Bertel