Configuring 2 NIC cards

This is a guess, not enough info.
Are the IP addresses on the internal nic, in the same subnet as the rest? Can you ping it?
Is the Nic bound to the same protocol?
Is the link light on, can you see anything from that server on your internal network. Can you ping your machine from the server?

This is a binding problem with the server? What OS?...

(assuming TCP/IP)

Are you saying the from your internal network, you cannot connect to the server through the "inside" interface? Assuming that you have no other routers, etc., then the default gateway on your internal PCs needs to be set to the IP address of the inside interface of your server. Also, those PCs and that inside interface all have to be on the same logical network (as far as address and subnet mask are concerned).

You likely also have to turn on routing through your server,to let the PCs talk out through your server, for example. In WinNT this is called "IP Forwarding".

Real Question: Is this what you really want to do?

In order to do what you have described, you need to follow these steps, and you need to know your TCP/IP stuff:
1. The internal NIC has to be configured with a static IP address within the same subnet as your internal network. It should be staticand it has to be an address that is not being used by any other host on the network. Do NOT put a default gateway address on this NIC - leave it blank. This NIC should be cabled to your internal hub.
2. Your external NIC will also need a static IP address, but that address has to be a public address that is leased from your ISP or, if you are hosting your own domain, then from InterNIC. Once you get this IP address, give this address to your second NIC - your ISP will give you an IP address, a subnet mask, and a default gateway address to use. This external NIC must be connected to a router or modem that in turn is connected to an external analog, DSL, ISDN or T1 line, not a hub.
3. You need also to assign your internal NIC the required WINS or DNS addresses to resolve your internal IP addresses to host names. If using WINS, you need to be sure that it is bound ONLY to the internal NIC, not the external one.
Some additional configuration may be needed depending on your emailmethod - Exchange, POP3, etc., etc. - and whether you have a firewall or proxy server. This is a bit complicated, so Good Luck! If you need further help, email me directly (synergy@synoffsys.com) and I'll point you to some TechNet articles that will help, too.