Enable PPTP in the security section of server/manager. Edit the users whom you want to give access to the VPN, and "turn on" PPTP/VPN within their settings.
Go to your win2K, or XP machine, create a new network connection in networking, choose a VPN connection, insert the public IP of your server, and give it (the connection profile) a name.
When you click on the icon, login as whatever user you have enabled it on, and you will connect.
Once connected, you cannot "surf" the network neighborhood, but you can access shares with shortcuts like
//server_IP/sharename.
I might not be completely right on, but it's fairly close. We use the PPTP/VPN connections everyday, and they work well.
For more info, remember, "google is your best friend"
Chris Curtis
Have a great weekend!!!!!!