Intel® Extended Memory 64 Technology is one of a number of innovations being added to Intel's IA-32 Server/Workstation platforms in 2004. It represents a natural addition to Intel's IA-32 architecture, allowing platforms to access larger amounts of memory. Processors with Intel® EM64T will support 64-bit extended operating systems from Microsoft, Red Hat and SuSE. Processors running in legacy* mode remain fully compatible with today's existing 32-bit applications and operating systems.
No, it is just like a athlon. It is 32-bit but is capable of running 64-bit applications so it looks like amd cant say their the only 64-compatible windows.
But Intel advertises as EM P4(w.e). It is extended memory so it can still do 64-bit proccesing. Amd runs at 64-bit and can do 32-bit as intel is 32-bit and can run up to 64-bit? Something like that.