Hi All, I think this has been covered when I did a search, but I'm slightly unclear. I'm debating if I want to upgrade my 4gig of ram in my june 09 17" macbook pro. My question is this: Can I either a.) Use one of the 2gig sticks in my computer already, and just get a 4gig module. or b.) Should I get a 4 and 2 gig set to make sure they match. I'm just curious if I need to get them together or if Ican swap different companies etc. Plus any negatives or positives from going either route? Thanks all!