Ok did you uplug the router.. if not do that and go back into and make sure of these things ...
Verify that your internal IP has not changed many routers allocate these as they power up, useally related to the socket port you use however, this is not always the case
You can find out what a machines internal IP is by doing the following, go to Start > Programs > Accessories > Command/MSDos prompt, in the box type in 'ipconfig' for getting the ip of one machine or 'ipconfig /all' to get all the IPs on that network.
Once your sure thats correct reset the ports.
Also make sure if your using your XP firewall that you have the ports forwarded there to.. sounds obvious but with updates XP likes to well.. change itself to protect you better.. lol
Let me know again