IT Employment

Hello,
I've been studying IT for MS certifications, and practice on my home network that consists of 4 PCs. I've got a question about VPN configuration in 2000 Server, and will be really glad if you could give me some insight. Here is what I'd liketo learn: While I manage to configure and use my RRAS Server as a VPN Server with NAT service on the PC which has the NIC to Internet (cable connection) besides a second NIC for the LAN, I fail to configure when I wish and try to configure another PC of my network which runs 2000 Server too with two NICs installed. Do I have to configure the Server that has Internet access as the VPN server? OR: Can I use another Server in the LAN as the VPN Server while the one with direct Internet access actsas RRAS NAT server?
Here is how I've configured my 4 computers to learn and practice RRAS Server topic:

PC1 (server 2000)= acts as DC with one NIC; holds AD, DHCP, DNS.
PC2 (server 2000)= acts as replication partner; with two NICs, one NIC is external for Internet connection; provides NAT service.
PC3 (server 2000): made a member of the domain as a stand-alone server, aimed to be used as RRAS/VPN server for remote clients; has two NICs.
PC4 (multi-boot with 98, NT4 workstation; 2000 Professional); for clients. One NIC for LAN, and also installed modem for a dial-up Internet connection.
All the server PCs TCP/IP settings configured statically/manually. No problem with DNS, DHCP (I use DHCP Server and DNS server, not those of the NATservice).
I hope I could explain things, and my question makes sense.
Grettings,
Bernar