A lot of good points. Nintendo IS a gaming company. It may be their success and their failure, but on the flipside of the coin, all of their effort and focus is on that industry. Microsoft has to develop the next Windows, Office, and other computer software whilst Sony has to design sound systems, electronics and such. Nintendo are working within their means and prospering while Sony and Microsoft are struggling to make a profit.

To throw even more light on this idea, it appears that Sony is taking a huge risk with the PS3, putting all of its eggs (including the Blu-Ray egg) into this basket:

Sony's PS3 Gamble