If they had crippled the Xbox to a dual-core then and only then will you find out we really need to move on FROM DUAL CORES.
What are you even talking about? The Xbox 360 uses a completely different architecture compared to anything you try to compare it to. I mean really, what the heck?
Dual core x86-64 CPUs are perfectly viable for gaming, the GPU is the only real thing that matters these days and has mattered for a fair while now...