Sharing a Cable MODEM

I’m trying to connect (share) my cable modem to my home Network using a NT Wkst with 2 NICs. The card connecting to the ISP gets dynamic IPs the other card I supply the IP.
With both cards configured I have no problems connecting to my network but can’t make the cable connection. If I disable the network NIC the cable connects.
I checked the routing table “ROUTE PRINT” and it looks correct. Still no cigar…
Am I missing something. I’m trying to avoid using a PROXY… Just want to ROUTE…

All comments are welcome..

Thanks…