I was recently having issues connecting to a server using remote desktop and ran across a very good reference page on the topic: Remote Desktop Tips for the SOHO User. Lots of screen shots and specific information. Reviewing this page, I learned about a utility from Microsoft called the PortQry (port query) tool, that allows you to query for specific open ports on a remote IP address. It's a command line utility, but there's a GUI version available. I downloaded the utility and immediately found that the remote desktop port (3389) was not listening on the remote server, which effectively ended my troubleshooting. I highly recommend it as the place to start for remote desktop information.