Complex sentence: According to Microsoft, it is a common misconception that the Xbox and Xbox 360 use a modified Windows 2000 kernel, for the Xbox operating system was built from scratch but implements a subset of Windows APIs.
Split into simpler sentences: According to Microsoft, it is a common misconception that the Xbox and Xbox 360 use a modified Windows 2000 kernel. They claim that the Xbox operating system was built from scratch but implements a subset of Windows APIs.