If you're trying to access your home/office using your public IP, your private Windows 2003 DNS server is of no use. As you've seen, the remote client has a private IP address that means NOTHING outside the confines of your local network. The only IP that provides access to your network is the public IP provided by your ISP. Since most providers use a dynamically assigned IP, it’s convenient to use a DDNS (dynamic DNS) provider like DynDNS.com or NO-IP.com. They provide a service that keeps a domain name updated w/ your public IP, even if it changes. You’ll need either a router that supports DDNS, or an ALWAYS ON desktop/laptop at home w/ DDNS client app, to keep it updated. In order to find a SPECIFIC machine, you’ll also need to use the port forwarding feature of your router.