Airport You can use one of these external adapters to access the newer routers. It works perfectly with my Tangerine MacBook which previously would not connect to my new Airport Extreme base station. Read the specs to make sure you have the minimal OS X version needed.
When you say Airport extreme, do you mean the base station or just connect using the wireless on your iBook?
It's worth noting that only the G4 iBook models have Airport extreme cards, while any of the G3 models have Airport cards. I believe the Airport cards will connect to the Airport extreme base station only if the security encryption has been set to WPA or WEP. It can not connect using WPA2
Check which model of iBook you have.