According to a leaked document, credited to Pete Isensee at the Xbox Advanced Technology Group, XBox 2 will be powered by three 3.5+ GHz IBM PowerPC cores, built onto one silicon die and a 500+ MHz ATI graphics processor. XBox 2 will have 256+ MB of unified memory and run a custom operating system based on Microsoft Windows NT, similar to the Xbox operating system. The graphics interface will be a superset of Microsoft Direct3D version 9.0. The document itself, emailed to xbox-scene.com, is car…