Overall, I think that the cost of goods sold is well below that of the revenue they bring in.
The issues of profitability come from other aspects of running the Xbox - developer moneyhatting, marketing, and other "ect" ideas. The Xbox 360 is most likely rather profitable right now, and is allowing for agressive spending on acquiring new IPs from 3rd parties.
However, Microsoft needs a more Nintendo-esque strategy: get more developers for first party projects. Microsoft has made hundreds of millions off of the Halo franchise. MS needs new IPs, and more staffing to go along with them: ultimately, making money as a hardware company needs to come from selling the vastly more lucrative software. Nintendo makes their killing on the endless, mindless Mario and Touch titles, not the hardware itself (having said that, the hardware makes them a tidy profit too).
Think about it: the 360 has about a 7.0 or even 8.0 attach ratio...Microsoft might make $50 a console, but if it sold a decent bit of 1st party software, (lets say 2 titles/console), then it's making more money via software than hardware. Nintendo does this very effectively by clogging it's system's software sections with 1st party titles, netting them billions.
Back from the dead, I'm afraid.
