XNA Math Library Getting Started
http://msdn.microsoft.com/en-us/library/ee418725(v=VS.85).aspx
XNA Math Library Reference
http://msdn.microsoft.com/en-us/library/ee415574(v=VS.85).aspx
XNA Math Library Functions
http://msdn.microsoft.com/en-us/library/ee415580(v=VS.85).aspx
XMVECTOR
http://msdn.microsoft.com/en-us/library/ee420742(v=VS.85).aspx
XMMATRIX
http://msdn.microsoft.com/en-us/library/microsoft.directx_sdk.reference.xmmatrix(v=VS.85).aspx