the core 2 chips have better ipc (instructions per cycle) 4 compared to that of the intel pentium d s 2 intsruction per cycle I think thats the biggest advantage the core 2 ghips have (better and mre efficient architecture )
i heard in 1 website tha athlon chips ccan communicate via internal bus due to hyper tansport and the fact that they r on the same die or sometin , maybe im wrong cant remember , but anyway6 this thread has made me understand dual cores better