dhcp server issues

[cfh]

I have a Linux computer (call it g1) that acts as a gateway router to the Internet for a internal LAN.  The computer has three Ethernet cards, only two are used at this time.  Eth0 gets it's IP and gateway from a dhcp server in the internal LAN and eth2 gets its IP and gateway info from my ISP's dhcp server.  The problem is that eth0 comes up first and the routing table gets the gateway that the other computers on the LAN get, which is Linux computer (g1).  Then eth2 comes up and gets it's IP from the service provider, but the routing table is not updated with the ISP assigned gateway because it already got it's gateway IP from the internal dhcp server.    I need  the routing table on g1 to be updated with the gateway IP from the ISP so it can find the Internet.  I know I could make eth0 the external card so it gets assigned the ISP gateway first, but other issues make that undesirable.  Any ideas on how to handle this? Is there a way to make the internal dhcp server not giv!
e a gateway IP to a specific machine (g1).