Networking question.

[coax31]

I have 3 computers and 1 laptop, a D-link 514 wireles router, and a Lynksys 5 port switch. One of my computers is a server with two NIC cards and is running windows 2003 Server Standard. I have a Comcast cable Internet. I want to setup a domain and use the router as a firewall in between the intenet and the server. Now the router uses NAT and DHCP and the sever will have routing and DHCP setup as well. Can I setup a static IP in the router and will it still be an effective firewall? How would you set it up?