Jay,
Wi-Fi Protected Setup or WPS is a somewhat new feature on most routers. However, I believe that the WRT54g was release prior to this feature. The installation disc for your wireless adapter is trying to circumvent network discovery and the process of entering a wireless password by using the WPS feature. Without using the installation disc to setup the adapter should still be able to connect to your Wi-FI network. Only use the disc to install the drivers for your wireless card and the wireless access utility. After you have done this:
1.Open the wireless utility and you should see available networks
2.Select your Wi-Fi network
3.If the network is open (not password proctected) you should be connected immediately
4.If the network is secured (password protected) then you will prompted to enter your password or preshared key
5.After entering the key you should be granted access to the network
Hope this helps
Blake Wright
Cisco SBSC Network Engineer