The Microsoft XPS Document Writer (MXDW) is a print-to-file driver that enables any application to create XML Paper Specification (XPS).
About Microsoft XPS Document Writer
http://msdn.microsoft.com/en-us/library/dd183313%28v=vs.85%29.aspx
http://windows.microsoft.com/en-US/windows-vista/Print-to-the-Microsoft-XPS-Document-Writer
Cheers,
Thomas