NAT on VPN Server 2003 ?

I am doing a project, i have an adia. In my network VNP system, I have VPN server 2003, IAS 2003, DNS, DHCP server 2003, Mail Exchange Server 2003. All of them are seperated but connected through a Cisco witch series 2500.I configure them to be a VPN system, it works well. Now, i want to use only public IP for all my VPN system, and I want to use NAT service on VPN Server (Gateway Server). How can I must configure all clients in my system can access the Internet, and remote computers can access my Web+FTP server in my system through VPN server 2003 ?
Please hepl me,thank you very much ?