If you look at the other threads around WiFi (there have been quite a few in the past week) you will notice that most members on ehMac seem to be using other brands of routers. My approach has been to get a router compatible with the PC card I was buying (I was running Win2k at teh time) for faster configuration. I then bought a PB12" with extreme and got full compatibility on the spot.
The bottom line is that everything is pretty much compatible with everything else. Make sure that you don't limit yourself by buying an 11Meg router: get a 54Meg one.