Only AirPort cards work in the AirPort card slot-the space isn't large enough for a full-sized card, anyway. Using a PCMCIA card would be fine, assuming you chose a card that has Mac drivers; this isn't as easy as it should be, but a little shopping will get you what you need.
As for 22Mbps, while the "dual mode" equipment is backward compatible with WiFi, you only get 11Mbps when you use standard WiFi equipment. You need both ends, computer and access point, to be 22Mbps to get the full rate. I don't know if D-Link has Mac drivers for their new 22Mbps stuff.