Hi, everyone. I an a question about HD and what RAm to buy. I have an Early 08 Macbook Pro 15" 2.5Ghz with 2GB ram and 250GB HD. I am looking to upgrade the HD with a new bigger capacity HD and looking for more ram. I am set on buying Corsair's Low Latency Memory (Corsair VSA4GSDSKIT667C4 CAS 4, 4GB (2 x 2GB) kit ). I am wondering if anybody knows if CAS 4 is better than CAS 5 and also, I am not set on what HD to buy. I was looking at a 7200 rpm drive with a lot of capacity. Here is what I have found so far that I like. I don't have the money to buy SSD. Samsung Spinpoint MP4 (HM640JJ) 640Gb for 90 WD Scorpio Black 500Gb Seagate Momentus XT 500Gb Seagate Momentus ST9750420AS 750 GB for 70 I don't know how good Samsung is compared to Seagate and don't know how good Seagate is. Will the Seagate Momentus ST9750420AS 750 GB work for a Mac OS or what? I have the WD Passport Studio 500Gb and it is full. So more space on the MBP is what I am looking for along with performance. The Momentus XT is too unstable to try. Has anybody used it yet?