If you use mac filtering, all you should need to do before anything else is type the mac address of the bit of kit into the allowed list. Though having just plugged in the BTHomeHub wireless jobby we got from BT free, with a faster connection for 2 quid less a month it was a total breeze getting the Wii, DS, Mac and PC onto the wireless connection, slighly concerning that the SSID is broadcast, there is no mac filtering and the WEP key can't be changed, but bloody hell it was easy
And the boss is buying our old wireless router off us as a backup for work
Oh and the BTHomeHub looks rather funky, now to go get the phone bit setup !