GuitarPaul,

I thought you may want to take a look at this.

The following link explains step by step how to join the domain using a VPN. It refers to Small Business Server, but the process is the same for standard server versions, however you can ignore steps 14, 15, and 16.

http://www.smallbizserver.net/Default.aspx?tabid=266&ArticleType=ArticleView&ArticleID=83

VPN Configurations:

Server 2003 Configuration:

http://www.lan-2-wan.com/vpns-RRAS-1nic.htm

Windows XP Client Configuration:

http://www.lan-2-wan.com/vpns-XP-Client.htm

You will also have to configure the router to forward the VPN traffic to the server. This is done by enabling on your router VPN or PPTP pass-through, and also forwarding port 1723 traffic to the server's IP. For details as to how to configure the port forwarding, click on the link for your router (assuming it is present) on the following page:
http://www.portforward.com/english/applications/port_forwarding/PPTP/PPTPindex.htm
The only other thing to remember is the subnet you use at the remote office needs to be different than the server end. For example if you are using 192.168.1.x at the office , the remote should be something like 192.168.2.x

Once this is configured you can then use services similar to how you would on the local network. You will not be able to browse the network unless you have a WINS server installed. Also depending on your network configuration you may have problems connecting to devices by name, though this can usually be configured.. Using the IP address is less problematic such as \\192.168.1.111\SharenName.

Taken from Rob W. on Experts-Exchange.

Bert
Pediatrics
Brewer, Maine