Currently own, PS3, Wii, PSP, DS and decent PC.
Reason not owning 360 is that despite its great game library, with above systems I felt I'm pretty much covered all I need. Though some games exclusive to 360 gets me interested, not yet to the point where I would spend $200-300. The games I am interested in are Lost Odyssay and Duels of Planes Walker. But with Free Online, Region Free Gaming, I felt PS3 is currently sufficing my needs as HD console. For motion control console wise, Wii is doing alright job, but haven't had played it for while.
So to me, it's basically Natal + Hardware upgrade i.e. the rumored Xbox Natal would do it.
Natal > Wii (motion technology-wise)
360 hardware upgrade >= PS3 (computational & graphical technology-wise)
This will make 360 the console of choice for me.
