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Broadcom says that they are Linux Compatible
Really? At least when it comes to wireless Broadcom has always loathed, despised and rejected supporting Linux. If you have a source, I'd be very interested.
You probably have two options for this card
1)The bcm43xx driver, which is in kernels 2.6.17 and later. However, given that the 4318 chipset still has some bugs, you might not get optimal performance. You will also need to create firmware with fwcutter if you go this route.
2)Ndiswrapper. If this card has a WindowsXP driver, there is a possibility that ndiswrapper can use it. If you go this way, check the ndiswrapper wiki and see if anyone has gotten that chipset to work.