I read the guide but I am still confused. Sorry. I also read about nine pages of the 8GB of RAM thread and now I am dizzy. I just want the 4GB TOTAL. So I should get the 2x2GB so I do not lose channeling (whatever that means). What do I get? I want to be sure what I buy is compatible and I have know idea what I am doing. Here is a screenshot of the "about this Mac" of my MBP. Thanks!