Three IBM-designed 64-bit microprocessors. The combined power of these chips means the Xbox Next will have more computing power than most personal computers. Earlier versions of these PowerPC chips are used in Apple Computer's high-end G5 PowerMac machines now.
A graphics chip designed by ATI Technologies with speeds much faster than its upcoming R400 chip for the personal computer. This chip will help the next Xbox to display games with the resolution of high-definition TV.
Compatibility with the original Xbox, which is based on Intel and Nvidia chips, isn't guaranteed. Microsoft is concerned it would cost too much money in hardware or in licensing fees to enable the Xbox Next to play old Xbox games. This is risky in part because Sony's strategy has been to maintain compatibility with its old consoles.
Source: Mercury News
Thats the way to grow your market share, no compatibly with the first Xbox.
Originally posted on Breaking Windows.