Thanks for the response Vladimir. I'm not targeting Itanium, I want to build 64 bit executables to run on processors with EMT64 running WindowsXP 64 bit edition or Windows 2003 64 bit edition.
One point of clarification, can I build EMT64 64-bit binaries using IPP 4.1 or do I need 5.0?
You can start with IPP v4.1, it was the first version which supports EM64T. Of course, in the next version you can expect more optimization and more functionality, but it is ok to use IPP v4.1 for your EM64T applications.