I forwarded port 3389 in my router and my XP Remote Desktop works perfectly. Maybe what has happened is that you have forwarded it to an IP that no longer exists. For example, if your Belkin router has a DHCP server in it and is enabled, and your computer is to set to get an IP automatically, then maybe the IP you set it to before is not what your computer has right now.
What you can do to get around this is manually set an IP on your computer. To do this you would need to open the Control Panel, then open Network Connections, right-click on Local Area Connection, click Properties, double-click on "TCP/IP". Here you'll see a whole set of boxes where you can enter numbers. Here's what you should enter:
IP Address: 10.0.0.x or 192.168.x.x (see below)
Subnet Mask: 255.0.0.0 or 255.255.255.0 (see below)
Gateway: The IP of your Belkin Router
Primary DNS Server: The IP of your Belkin Router
The IP address will depend on what the IP Address of your router is. If it's 10.0.0.1 for example, then you should set your computer to 10.0.0.2 and then set the Subnet Mask to match that of the Router's. You should be able to find all of that information in the Router's configuration. Your IP doesn't necessarilly have to be 10.0.0.2, just as long as it's different from the Router's, obviously. If you Router is 192.168.0.1 then you would need to set your computer's IP to 192.168.0.x where X is any number between 2 and 254.
Once this has been done, go back into the forwarding section in your router's configuration and then forward port 3389 to your computer's IP, whatever you just set it to.
Hope that helps. ;-)