Here is the setup:
There are six computers, five Windows XP Home and one Mac (running 10.3) in an office with Windows 2000 Server. Right now, there is a DSL modem/router (with a static IP) that is performing DHCP and acting as a gateway to the internet. The router is then connected to a switch, which the other computers and the server are connected to. I set Active Directory up, then realized that XP Home computers can't connect to the server for authentication purposes. The client is not willing to upgrade.
First and foremost, I need to set up a VPN in the office. I am somewhat familiar with how to do this. The server itself has only one NIC, but I can connect the DSL Modem (which I will have to swap in place of the modem/router) through a USB connection directly to the server. Since the modem will be directly connected to the server, how do I set up the other Windows computers (I can figure out the Mac on my own) so that they connect through the server to access the internet?
Also, how do I appropriately set up DNS so that those connecting to the network through the VPN can access the network? I would appreciate if someone could point me in the direction of some entry-level guides to setting up DNS.