I built this for my mother-in-law to reduce the clutter on her desktop and will mount with VESA mounting screws on the back of her 21" monitor.
The fan mounts from the bottom of the motherboard with special standoff screws. I laid the fan upside down on a hard surface, installed the CPU on the motherboard, put the thermal paste on the CPU and then flipped the motherboard over and visually aligned the motherboard holes with the fan screw holes. Then I tightened the fan screws on opposite sides, a little bit at a time to uniformly put pressure on the heat sink.
Once that was done, I put the I/O panel in the case. In retrospect, I should have attached the wi-fi antenna mounts to the I/O panel first to make it easier to tighten the nuts on the back. The motherboard slides in easily from either side of the open case (not very easily from the top). I was able to screw the motherboard down to the built-in standoffs on the case bottom and assemble the rest inside the case without any difficulty.
Then, I inserted the memory, mini-PCI wifi card, pico power supply, power led, switch and front panel USB 2.0 header. The 192W power supply brick uses a DIN connector, so the case had to have a ring removed and the female DIN connector screwed to the back of the case.
The supplied hard drive mounting bracket cleared the cpu fan case and mini-pci card with no problem. I wish I had a shorter SATA cable, but the right angle end fit in SATA_3 (covering the other slots) and I could fold the standard cable up in the space. It's not like I'm putting 2 drives in here.