I really want to have an SSD in the main drive with a hard drive in the optical bay. I have seen that apples ssd is not as fast as others I can buy. I also know that apples stock hard drive won't have motion sensor in the optical bay. I'm not sure if i should get the 128SSD or 500g 7200rmp when i order my 15 mbp. What is the best choice without having to buy 2 3rd party hard drives.