Only a true AirPort card will fit in the internal slots in iMacs, iBooks, TiBooks, etc. These cards are not really PC cards, and they have no antennas, only a connector for the built in antennas in the computer. I think the iMac needs a special bracket, too.
The Cisco card will work (if there are drivers for your version of MacOS) in a PC card slot, but again, nothing but an AirPort card will fit in the internal AirPort card slot.
The Cisco card will work (if there are drivers for your version of MacOS) in a PC card slot, but again, nothing but an AirPort card will fit in the internal AirPort card slot.