Some aspects of the Xbox 360 have changed since its launch in 2005, including the addition of an HDMI port, built-in Wi-Fi, 1080p support, and two all-new system designs: the Slim system and later the 'E'. The core hardware, however, hasn't changed much.
Why Microsoft Switched from Intel to Power PC for Xbox 360 | MVG
Here you will find the full hardware specifications for the Xbox 360 video game console.