I'm going to buy the new macbook pro when it's released but I was wondering if I bought the MBP with 2gb ram and then bought crucial 2gb ram to make a total of 4gb. would the crucial and mac ram be compatible together or if i would have to buy 4 gb crucial and not use the mac ram at all. Also does the macbook come with 2x 1gb or 1x2gb and how many slots does the MBP come with? 4? Thank you