There seems to be a lot of people unsure of kinect functionality, not just in poserverse. From what I've been reading off various forums is that the xbox kinect will sometimes work on the windows sdk, but not natively and there's no official support for it. Others say it works just fine. Some have claimed burn-outs of a lens adjust feature. 

Either way, if I get one I'll go with the windows version. It sounds to me that it would be worth the extra price for the additional features, plus the warranty which would likely be void if I used an xbox kinect on windows and something went wrong. I don't have an xbox anyway, as I don't play console games.