You learn something new each day...
Still, they have 3 Opteron motherboards, 2 of them in proprietary format and one in SSI EEB, not only getting hold of them is hard, finding a SSI EEB case and power supply is near impossible where I live. Hardly a competition.
On the other hand they have ATX Xeon boards... Looks like one fine in antitrust case wasn't enough.
I know that ECC isn't used in home computing, but this computer will be used as a server. Together with WD Velociraptors and Phenom II X6 1090T will be faster than any server that isn't at least twice as expensive. And I do include the cost of rack mount chassis and hot-swappable backplane for the drives. Hell, I could even include a redundant power supply and still outclass any other server in price/performance ratio at this performance level.
Of course, if I had to manage 30-50 or more servers, I would go the HP, Dell, Fujitsu route. The "this computer doesn't work, take it and fix it" support is hard to beat. On the other hand, Google is using regular computer gear for their datacenters.