Airport trouble with imac g5


In my house we just got an imac g5 so I installed the airport extreme card from my power mac g4 into it. But I can't get on the internet with it. All the other computers on the network can access the internet, but the imac. the imac can broadcast it's ethernet connection to the other computers so i know the cards not broken... plus the card worked in my g4 well... anybody know any ways this problem may be fixed?
Do you get any signal? How does your network look like? Are you using a router? If so, check your router settings and turn off WEP, WPA and any MAC filters.
You may also have to give permission (in Airport Admin) for the iMac to access the network. Check that along with that Zammy-Sam suggests.