I just bought an airport express and extreme. I was just wondering how I could have the extreme as the central station and, the express as a reciever which could add my desktop pc to the network using the express' wireless. Appreciate your help
In the Airport Express, just set it to "Join a Wireless Network" and enter your WLAN configuration as if you were setting up a client on your network (which you are).
Then set under the Internet tab, set Connection Sharing to "Off (Bridge Mode)". This will turn off the DHCP and routing stuff and will bridge the ethernet jack to your wireless network.