Alright I went through the mac - intel based ram guide, but got a question or two. I have a brand new MBP, I forget the exact specs but its got 2 gb ram (I'd assume 2x1gb from the factory). I'll get it back tomorrow from the CIT department because they messed up installing some of the software we need from school . Now what way do I check to make sure its manufactured after say April 08? I assume it is, but just want to make sure as I am about to go out and buy DDR2 800 (PC2 6400) memory. There is a very good deal on OCZ 2x2gb set here on newegg. I have always been happy with OCZ memory, have used them a lot on my windows boxes. However, one of the 'reviewers' comments that it didn't work on his Penryn MB. I assume I have this same family of processor? http://www.newegg.com/Product/Product.aspx?Item=N82E16820227251 Why wouldn't it work? ANybody tried this particular type of memory? Crucial.com is telling me to get PC2 5300 according to their selector...but they do have PC2 6400 2x2gb kits available on newegg though its more expensive than the OCZ I posted about. Also, according to some of the reviews on these ddr2 800 units, they won't run at 800, only 667mhz on some of our computers? Are these people wrong?