I´ve just started using my Macbook unibody from 2008 alot more than I used to. I see now that lagging occurs more often than before, because I run alot of programs. So Im thinking of buying more RAM. But just a little bit more. I could open my machine and look, but I thought it would be easier to ask first. Are there free slots in the MAcbook? Do I have to change the ones that are already there, out with some new, or can I buy more RAM and put them in some available slots there? So what kind of Ram does the machine use anyway? I see OSX tells me its DDR3 and 1067 mhz. But there are more to RAM naming than this. Usually I need to know something like "PC" and a bunch of numbers right?