Routing WAN IP’s to the LAN side of a network

Hi,

I was wondering if anyone could help me with this. I am running a wireless network. The main server/router is running Windows Server 2003. I have RRAS and DHCP enabled and all is working fine.

I have a person on the LAN side of my network that would like a Static WAN IP to run a mail server on. DHCP has already assigned an IP for the LAN side and he can surf the net just fine. So the question, how can I setup my system to assign a Public WAN IP to this person or route traffic so the world sees him as the WAN IP I assign and not the WIN 2003 NIC IP?

Thanks for any help!

Dean