I wanted to install an SSD in my MBP 15". I see with istat that I have only used 75 gbs of my available 250. I assumed that a 120 gb SSD would be enough to clone my old drive.Bought a crucial BX100 120 gb SSD. Disk Utility says that the 120 gb drive is not big enough to perform the cloning process. Any ideas why my math didn't work out or is there perhaps something else I may have missed.