If you'd like more information about ATX or other form factors, Teleport has a great web site. We happen to like this case because of the slide out tray used to mount the motherboard. The case is available with a 300 W or 235 W power supply. We also offer the PC Power and Cooling Personal Mid ATX tower. This enclosure does not require a screw driver to take off the lid.
ASUS cases are also a popular choice for our customers.
These are solid steel cases. This is based on a design by Western Digital. The expansion slots are on a single riser card which is mounted onto the planar board. Again, Teleport has extensive descriptions of the design. NLX is a low profile option.