Mounting the motherboard to the removable tray is a snap and the tray is deep enough to handle the larger micro-ATX size. After reinstalling it and the other drive cages, all that is left is to mount the power supply. The bracket that holds this in place is removable too, but it is difficult to reach the hard drive cage (to plug in the power) with everything else in the way. It might actually be easier to put the power supply in with the drives and slide the motherboard tray in last.
As far as the power supply goes, there is roughly 8" of space front-to-back to fit some of the larger 700-800w units. If you put an optical drive in the top bay that clearance probably drops a ½" or so due to the cabling coming off the back of the drive. In the lower bay it is below the bottom of the power supply. In this example I'm using a 450w that is only 5½" deep.
Thermaltake claims the LANbox is capable of housing the nVidia 8800 cards, however I measured only a little over 9" of room from the back of the case to the edge of the drive bays. That's enough space to fit an 8800GT or GTS as those cards are exactly 9" in length, but the GTX and Ultra are 10½" which is too long. Unfortunately, detaching the side-mounted 3½" floppy bay is not an option, so either stick to the smaller cards or break out the Dremel tool.
Ahead, final thoughts and conclusion.