Setup Cable Modem on Windows NT Server

I am trying to setup my cable modem on Windows NT Server 4.0. So far I haven’t been able to connect. I think it is because of the TCP/IP configuration. Any one can point me in the right direction?

Some details: I have two network cards on the server. One for the LAN and one for the cable modem. I am using DHCP, which forces static IP addresses for the network cards. The problem is that my server provider requires that the IP is allocated dynamically (no fixed Ip address). What would the TCP/IP configuration for the NIC connected to the cable (i.e. IP Address, Subnet, Default Gateway).

Thanks for the help.

Charles