I have an MB871LL/A which is also 4,1. Its a 2009 Quad Core Nehalem model. Here is the dilemma, Sata 2 or Sata 3? I have received all sorts of answers from everyone including Apple Care. Should I get a Sata 2 or Sata 3 drive? The manual says the computer runs Sata 2. Western Digital makes a Sata 3 whcih of course is 6 gb/s of transfer for a higher price. Again I have received many variations to this question. The bottom line question is this: Can I get the full benefit from a Sata 3 drive at double the transfer speed just by installing the drive? Apple claims I'm wasting my money because the machine will run it but it will drop it down to Sata 2 speeds 3 gb/s. Others claim if I get a card for one of the open slots and connect the drive to the card, it will run at Sata 3 speeds. Can please give me the real answer? PS: Apple tech support should be humiliated with their various responses thus far and I'm shocked they cant even answer an easy question like this!! Thanks!