As you are using XP SP2, I would definitely recommend using Windows' own wireless networking software, it is much more straightforward than Belkin's. Plug the PCMCIA card into the laptop and let Windows "find new hardware". Follow the wizard and select the option to install from a specific location. Insert the CD and 'browse' to the Drivers folder. If the CD "autoruns" to install the Belkin software, just Exit from it.
With the drivers installed, you will now have a "Wireless Network Connection" in the Network Connections folder. Right click it and select "View Available Wireless Networks". After a few seconds while it scans, it should display the SSID (network name) of your Wireless Router and you click the Connect button at the bottom. If necessary, you will be prompted to enter the WEP/WPA encryption key which will have to match the one you set up in the router. It is that simple. Once Connected, and as long as you don't click the Disconnect button, it will connect automatically in future to your wireless network when the PC is booted and provided the WiFi network is available.
<<< will i need to uninstall anything (apart from taking the router out) before i try to set up the wireless network? >>>
No, because a router isn't installed as either software or hardware in a PC - it is a network device that the PC connects to.