If you're running Windows 7 (and it likely applies to Vista as well), I have not been able to get any game or web servers visible externally on that operating system. I periodically search for new answers and test new things, and if I discover the problem I'll let you know. Disabling or creating exceptions in the Windows Firewall, setting up port forwarding on your router, and disabling antivirus does not help (although most of those will be required first steps), nor does relaxing file permissions on the folders in question. It's something else and there isn't readily available documentation on the cause available on the internet.