Can you access the Internet via the laptop as well as the PC?
All the router does is broadcast a wireless signal, and provided its modem is online it will distribute the broadband connection to any computer within range. Are you saying that the laptop can't access the Internet, or are you saying that neither computer can?
If it's that you want to network the two computers then you'll need to run the WindowsXP networking wizard on both machines. What type of network card do you have in the PC - is it wireless or a conventional LAN card? If it's a LAN card you'll obviously need to connect it to a LAN port on the router before your network and/or Internet connection will work on that machine.
I may have the wrong idea of what the problem is - post back with a bit more detail if that's the case.