I have tried WPA+WPA2 and also WPA on its own... None work
With no security it connects no problem
I am thinking the mac must have something stored that needs to be cleaned but no idea.
I did have problems with my iBook at the time in regard to the battery life and the battery clock time gets lost because it loses all power before the time/date is saved. I don't know if you suffer such power problems, but it was around this time I started experiencing problems with Airport.
I don't use my iBook anymore though as the crappy thin power lead has frayed for the 2nd time now and I can no longer charge it. Shame its not MorphOS compatible otherwise I could probably buy a new cable and sell it to an interested MorphOS user.
I don't miss the iBook though as its so frigging slow playing videos on youtube and flash... ahhh lets no go there.