Apple’s original AirPort card appears to be physically incapable of WPA/WPA2 encryption. The software doesn’t tell you, of course — it just silently fails to work.
Where did you find an AirPort Extreme PC Card? Apple AE cards are a different, larger size, and I seem to recall that even the PC Card shaped original AirPort cards wouldn’t work in a normal PC Card bay, only in a dedicated slot.
My 800MHz DVI TiBook seems to have a bad AirPort card slot — every card I’ve tried in it died within a month, so I’m very very interested in this thread.