HI all!
I have a Dell D620, with Intel graphics card and Intel. I'm running Snow Leopard 10.6.8. I changed the wifi card to a Broadcom 4321 from a HP laptop. Theoretically work natively, but doesn't. After a lot of search, the solutions that i found was: changing or patching the IO80211Family.kext. I only found a post relative to HP laptops that changing the SMboardproduct key on smbios.plist to Mac-F22788A9 would be sufficient.
I changed the key, previously was Mac-F42C88C8, and after reboot the wifi card detected!!
A simple solution. I think that is valid for others laptops.
Sorry for my english, it's my little contribution.