I am trying to take advantage on the holiday deals. I have never upgraded the memory on a computer nor do I know much about it. I have a Mid 2009 Macbook Pro with 2.53 GHz Core Duo, 4GB 1067MHz DDR3. I am looking to upgrade the memory, 6-8+ GB. So I have a lot of questions: Since I have two memory ports, can I put a 2GB and a 4GB in the other? Is there a limit to how much I can put in this model MBP? Lastly, do I need to match up the MHz? Like if I buy two new memory cards at 1333 MHz, will that work?