My new Mac Pro arrived today and I had a 2 TB Hitachi Deskstar 7200rpm HD waiting to install in the new computer. The Mac Pro is *amazingly* simple to open and upgrade. I flipped a small latch on the back and the side panel dropped down. Sliding out one of the HD tray (you can see it missing in the upper left of the screen. Using finger screws I attached the tray to the HD and then propped it up next to the box. To install, I just had to slide the tray (with the HD) into place, push a little wee bit so it made a connection, and wallah! Putting the cover back on and closing the latch locks the HD's in place.