i think it is wii,if it failed then im not sure if ninty would of made another console,but in the case of DS if it failed they could have always changed the nexg hand-helds name back to gameboy

Youve got pretty much everythiong covered. If the home console failed, NIN would have to rely purely on the handheld for the income, or wait for the next gen console. With the ds, they could have always went back to the gameboy. They considered the ds the '3rd pillar' anyway.

From a hardware design perspective I would say that the Nintendo DS was far less risky because the DS can operate as a (pretty good) conventional portable system if you don't use its new features. At the same time I would say that the Wii was far less risky from a business perspective because it was clear that their approach had some merit before they demonstrated the Wii for the first time.

actually I say the DS...wanna know why?
the DS was a test subject..that's why they released the'true' DS later (Lite)

looking at the DS success they knew the Wii could not fail

problem is: the Wii is outdoing the DS 0.0

I'd say the DS because at that time 80% of their profits were in handhelds. Had the DS lost against the PSP it would have been a fatal blow for Nintendo. Sure they would have tried to bring out another Game Boy generation, but the fat profits that come from market domination would have been gone and the stock would have plunged. Nintendo would have become a takeover target.

ds becuase it was a test basically to see if people like innovation, they could of lost their handheld king crown, so then the wii would'nt have been made if they did'nt like it.

 i doubt they would of lost the hand held crown,they could of just change the name back to gameboy

I'd say the DS; but myself, as soon as I saw the 2005 E3 movies of Nintendogs, I didn't see how it could fail...

^but like i said if wii failed they probably wouldnt make another console,so dont you think that was a bigger risk?

Yes. Definitely.