I want to know whether the computer always boots from the disk that is plugged in to the primary hard disk location. Here's why: I'm going to replace my Optical drive with the default disk that came with the computer and want to have Snow Leopard on a new Intel SSD. So: 1. I take out the default HDD. (Snow Leopard is installed on it already from Apple factory) 2. Plug in a blank SSD in its location 3. Boot from OSX DVD and install Snow Leopard on it 4. Replace DVD bay with the default HDD ..but what happens now if I boot ? Now there are TWO disks in the computer with Snow Leopard installed on both. Which one will the MBP boot from ? Thanks for your answers in advance, I appreciate it as always !