"For the first time, Microsoft has posted a free public preview of a 64-bit version of one of its operating systems, opening up the AMD-based Windows XP 64-bit Edition for 64-bit Extended Systems for one and all. While the company has actually been testing the software since last fall--a previous beta was distributed at October's Professional Developers Conference (PDC) in
"MICROSOFT HAS MADE a trial version of its hotly-anticipated Windows XP for 64-bit AMD chips available for download.
"The trial OS is designed, says the Vole, for systems sporting Athlon64 or Opteron processors. Don't bother trying it on an Itanium, it advises." -- The Inquirer
People have short memories. There was a Windows Advanced Server Limited Edition (basically Windows 2000 SP2) for Itanium, essentially as a preview release, before Windows Server 2003 came out. Windows XP Professional 64-bit (for Itanium processors) is listed on MSDN Subscriber Downloads as released on 26th March 2003.
Most Itanium workstation systems will have been purchased with Windows preinstalled, if the user wants Windows. An Itanium cannot run a 32-bit x86 operating system, it must have a native OS (IIRC). By contrast, an AMD64 system can still run 16-bit code in standard mode, and can boot a 32-bit operating system, so there are currently AMD64 systems out there running the 32-bit versions of Windows.