Removing the three screws I showed earlier allows for the motherboard tray to lift up and slide off the chassis. Antec has already looped a wire management strap to the tray, I assume to help manage the wires coming from the rear I/O panel as well as your choice of video cable. The tray is designed to mimic the angular designs of the Skeleton; this time the design should aid in allowing air to the back of the boards components, helping to keep things cool from underneath.
Again we have the motherboard tray, but this time with the board, RAM, and processor installed and ready to get put back into place and get hooked up to the Skeleton's wiring.
While I was prepping the Skeletons removable components, I also mounted my OCZ GSX 700 watt power supply in the tray. Mounting is done simply by screwing in four screws into the universal grooves and holes in the tray.
As the baggies designate, there are specialized screws to use on your drives. This is a shot of the hard drive screw mounted in the left side of the drive to grab into the quick locking system.
For the exact same reasons, you add a silver screw from the optical drive bag to the right of the DVD drive.
Once the screws are added to the correct corresponding holes, you can just plug them in and slide the drive into place until the tab clicks into place. For normal use with little movement of the Skeleton, this is plenty secure enough to hold the drives in place. However, if I were to travel with this case, I would add a screw or two for security's sake and peace of mind.
Yet another aerial view of the Skeleton, but this time with all the components in place. You can see the 250mm fan covers most of your motherboard and should have no issues aiding in cooling vital components.