You shouldn't have to remove the internal airport. That said not sure if the airport drivers work with that card or not ... guess you'll have to try and let us all know
if it doesn't you can try googling, there are a couple of other wireless drivers for OSX, both free and commercial. I know that Tiger removed support for quite a few non-apple cards. I have an Orinoco Silver that used to work with the built in drivers that no longer does :/