Before activating a closed source module, one should disable the built in open module. Assuming it's built as a module, which in any self respecting desktop distro it should be, you should blacklist the open ones for the, I assume closed source ones, being a mac likely broadcom chipset of some kind. The procedure is a bit unclear to me for ubuntu users, but there should be a blacklist hiding somewhere in your /etc dir.
Ndiswrapper is a way to go, though it seems a little too hackish for me. These days you can get linux native drivers for all but the most esoteric of wireless chipsets.