http://msdn.microsoft.com/en-us/library/aa480152.aspx http://topic.csdn.net/u/20070206/16/55ad7fcc-99e3-47db-acc7-92c9da05f322.html
http://blogs.itecn.net/blogs/ahpeng/archive/2005/09/13/System_5F00_Security_5F00_Context.aspx
http://forums.microsoft.com/china/ShowPost.aspx?PostID=3564373&SiteID=15
