Using two nic cards on a server 2003 box.

I have a 2 Windows Server 2003 servers, one is my DC & DNS server & the other is my DHCP server. I have a total of 2 laptops & 1 desktop on my network. Both servers have 2 nic cards in them. I would like to configure them so that the servers are hidden from the outside but my pc's can still connect to the servers for DNS resolution & DHCP resolution & connect to the internet. I have a D-Link DIR 615 Wireless router that is connected directly to an internet connection. I have a 2 D-Link switches, one 8-port & one 5-port. I am a MCSE student who is trying to get an understanding of how to configure my servers to get the best security. Someone please give me some guidaince...