That is insane, I love it!
while this is a bit late seeing as you've already got the bits (well done on the sponsership btw

)
The only thing the vagely worries me is is that 4670 actually anybetter than the 9300 onboard?
Might be better off leaveing out the graphics card.
Also might of been an idea to go the AMD route, so a socket AM2 mitx board with 780g chipset and pci-e
Then you could use the hybrid crossfire
Although thinking about it I think the 9300 chipset supports hybrid SLi although not sure what nvidia card you'd need to suport it
On a side note, umm are you planning to cut a hole in the top so that rad&fan can actually draw in/push out air?
Would of thought it would be better to have perspex on the front and mesh on the top.
Mesh front and back on a normal pc case works because you have fans drawing the air through.
As the motherboard tray is effectively forming 2 cells how about this for a layout.
Back of case, perspex above the tray, mesh below.
Cut an air vent in the tray towards the front.
Mesh on the top, rad fan sucking air through the rad and pushing ait out of the top.
In theroy air will get drawn into the harddrive&PSU cell at the back, flow past the drives, get drawn up into the upper cell, past the memory and sucked up through the rad and out the top.
An additional vent could be added below the graphics card to help feed that with cool air.
http://www.scan.co.uk/Products/JandW...X-HDMI-DVI-VGA