The Windows 7 remote desktop viewer that comes installed with the os will only connect to windows machines using the rdp protocol. I agree with most of the others that it would probably be best to install a VNC viewer on the Windows computer and use the vnc sharing built in to Ubuntu 12.04. Also this will allow you to connect to your remote Ubuntu machine from anywhere if you configure port forwarding on the router. For a quick guide with screenshots on how to set up vnc sharing on Ubuntu 12.04 follow this link: UbuntuLinuxGuideUbuntuLinuxGuide
