Apple Airport Express – WDS Remote
I thought I’d better start encrypting my wireless LAN at home. I had been using just a MAC address access list but with a another couple of wireless LANs appearing in the neighbourhood some extra security could be good.
I had some difficulty to get the Wii working with WEP so tried WPA which worked. Of course then the LAN in the attic which is connected by an Airport Express acting as a WDS remote stopped working.

I’d forgotten the rather obscure and seemingly undocumented procedure to set this up but found it again here :-
http://forums.macosxhints.com/archive/index.php/t-27269.html
Reset your airport to start from scratch. Use a pen to press the reset button and hold the button without letting go while unplugging the device, wait 10 second, replug, (keep holding!), wait until you see the green light flash four times. Let go of reset button. Wait 45 seonds.
Run the Airport Express Assistant.
Select: Set Up a New Airport Express
Select: Connect to my Current Wirelss Network, and place a Checkmark in the box for Extend the Range of my Airport Wirless Network
Tell the assitant to join your existing network, name your Airport Express and Quit.
Open the Airport Admin program
Select the new Airport Express basestation that you just configured (above)
Click on Configure
Click on WDS tab
Put a check in the WDS box and select “remote” from the drop down menu.
Gareth mentioned that the DS only does WEP, oh dear.