You can use Remote Desktop Web Connection to connect to a remote computer over the Internet. To do this, the remote computer must be running Windows Server 2008, and Terminal Services Web Access (TS Web Access) must be installed. (For information about installing TS Web Access, go to Terminal Services Web Access (TS Web Access) on the Microsoft TechNet website.) Here's how to connect to a remote computer using a web connection:
1.Open Internet Explorer or another web browser, and type the URL using the remote computer's name or IP address, followed by /tsweb/. For example:
•If the computer name is MyComputer, you would type http://mycomputer/tsweb/.
•If the IP address is 192.168.1.120, you would type http://192.168.1.628/tsweb/.
2.On the Remote Desktop Web Connection logon screen, in Connect to or Server, type the server name (the remote computer name), and then click Connect.
3.Type your user name and password, and then click OK.
When you are ready to disconnect, log off and then close your browser
Note: If you can't connect to the remote computer and you are using a firewall, open TCP port 80. For more information, see Open a port in Windows Firewall.
for remote desktop, the port #3389 should be opened!
check this Post http://windows.microsoft.com/en-IN/windows-vista/Connect-to-another-computer-using-Remote-Desktop-Web-Connection