I don't know if this sheds any light or adds to the confusion.
I have an iBook with an airport extreme card installed and I have an Airport Extreme base station in my apartment. Reception on my iBook has been spotty at best ever since I got the thing about 6 months ago. Then last week it quit working altogether for a couple of days. then it seemed to come back, but by then I had followed all sorts of (bad) advice and lost the settings for my network and couldn't get connected even though there seemed to be a signal.
Then I started to travel with my trusth iBook under my arm in case I wanted to play Snood while on the road.
In the Minneapolis airport departure lounge, I opened the iBook and found a live network that I could tap into (after I gave them my credit card number) that was great.
Then I arrived in Houston and turned on the iBook to show my brother something and there was a "FREE" wireless network that I could tap into. (I don't know whose network it is, but they haven't asked for any money so far)
SOOO!!!! It is not the computer or the airport card that caused my problems since both work fine when away from home.
It's definately something with the base station.
Take care, M