I wanted to do the same thing with my new MacBook Pro. It came with four gigs of RAM, but it is capable to hold eight gigs. So I bought it right off the shelf at Best Buy. Before installing it I went to the Apple store to ask about the warranty. Good thing I did, if you open a laptop and install memory you void the warranty immediately. I then asked if the Apple store could install it, they said no they only work on IMac's. So I returned the memory to Best Buy.