I'd think twice about the case.
I have the SG05 and its a POS.
The built quality is poor with sharp edges and the case not fitting together well. It rattles like a mofo from the hard drives and there is very little space to fit things in.
There is no sound insulation at all as the walls are just a piece of aluminium with ventilation holes cut in them.
The cube form factor also isn't as practical as you'd think. The case is still wide and high. I got totally fed up with the noise from mine and bought a p180 - total opposite of a small pc. Much happier tho!
I also built a slimline HTPC based on the ML02 and I am very happy with that. It is almost silent and the slim form very practical for a home theatre unit:
http://www.digitek.net.au/2009/10/silverstone-ml02-htpc/