I'm thinking of getting an iMac since it looks like the next generation is going to be announced soon. I want to have a SSD for start up and my core programs. It seems pretty expensive to have apple install it so I was wondering if it could be used externally? My goal is to have 2-3tb HD with a 40-80gb SSD (only looking to put OS on it along with my office for mac programs, aperture & iTunes)