I'm very sorry if there is already a thread out there. I've been struggling to find answers for my macbook upgrade, I own a Macbook "Penryn" 13". My Specs are: Mac OSX Version 10.5.8 Processor: 2.1GHz Intel Core 2 Duo Memory: 2GB 667 MHz DDR2 SDRAM Model: A1181 I'm afraid of my purchase for the G.Skill 4GB 200-pin DDR2 SO-DIMM DDR2 667 (PC2-5300) Laptop Memory for a few reasons: 1. I am not sure that it is capable, I've surfed the internet and most do not mention this RAM piece (I might not be searching properly). 2. Many customers buy the 2x2GB 200-pin DDR2 SO-DIMM 667 (PC2-5300), but the model is basically the same with the 4GB piece, will it still work? 3. Will my laptop still be able to run with the default 1GB RAM piece sitting next to it? 4. The picture of the RAM piece looks quite big, will it even fit in my macbook? Here is a link to the product: http://www.skycomp.com.au/item/G-SK...O-DIMM-DDR2-667--PC2-5300--Laptop-Memory.aspx I'm ordering from an Australian company so it will save trouble.