How do I share a clients net conn. on a LAN w\ Server 2003 DNS?

I have a client with XP sp2 and an internet connection on a LAN w\ Server 2003 set up w\ DNS and static IP’s. How can I share the connection with another client on the network, and still access the network without changing my servers IP?
I am willing to change all the clients IP’s if I must and am also willing to add DHCP role as long as it doesn’t change my server IP.
Please Help Me!!!