Windows NT protocols, subsystems go by the boards in x64
ENT News | at | by Mike
Some of Windows NT's oldest subsystem and protocol friends will be left behind when the codebase moves to x64.
Microsoft uses the x64 name to designate operating systems supporting the 64-bit extensions to the x86 architecture. The operating systems support the AMD64 architecture and Intel processors featuring Extended Memory 64 Technology. Microsoft's x64 versions of Windows Server 2003 and Windows XP are currently in the Release Candidate testing stage and are expected to ship in the first half of this year.