Hello All, I am looking to purchase a mbp and want to upgrade the RAM myself to save a few bucks. Being cyber Monday there are a lot of deals going on. I know that Apple sells the mbp with 1333 MHz DDR3 SDRAM, all the deals that i have seen have 1333MHz DDR3 SO-DIMM memory sticks. My questions is what is the difference? and will the cheaper SO-DIMM sticks be compatible? will they run smoothly? Thanks in advance!