The only way you could really compare the two would be to use mips (million instruction per second), this is because like the other two have stated, they were both built for different purposes.
AMD Phenom II X4 940 Black Edition 42,820 MIPS at 3.0 GHz 14.3 3.5 2009 
ARM Cortex-A15 (Quad core) 35,000 MIPS at 2.5 GHz 14.0 3.5 2010 
Intel Core 2 Extreme X6800 (Dual core) 27,079 MIPS at 2.93 GHz 9.2 4.6 2006 
Xbox360 IBM “Xenon” (Triple core) 19,200 MIPS at 3.2 GHz 6.0 2.0 2005
AMD Athlon FX-60 (Dual core) 18,938 MIPS at 2.6 GHz 7.3 3.6 2006 
As you can see, the xenon is slightly faster than a dual core Athlon FX-60, but by todays standards, the ARM Cortex A15 Quad core, is nearly twice as powerful, this is a mobile phone/tablet chip that will be in devices early next year. But to answer your question, i would say the Core2Quad is a lot better equipped for handling games than your XBox.