Microsoft has released an AMD64 version of Windows XP
"Welcome! If you have a 64-bit ready PC, you now have the option to receive trial software for Windows XP 64-Bit Edition for 64-Bit Extended Systems via CD or download. Read below about the different options for obtaining the pre-release software, and then use the links on the right to register to order the CD Kit or download product files. Please note that in either case, the pre-release software is time-limited and will expire in 360 days
Windows XP 64-Bit Edition is designed to address the most demanding needs of technical workstation users who require large amounts of memory and floating point performance in areas such as mechanical design and analysis, digital content creation and scientific and high-performance computing applications."
ntcompatible.com
"Welcome! If you have a 64-bit ready PC, you now have the option to receive trial software for Windows XP 64-Bit Edition for 64-Bit Extended Systems via CD or download. Read below about the different options for obtaining the pre-release software, and then use the links on the right to register to order the CD Kit or download product files. Please note that in either case, the pre-release software is time-limited and will expire in 360 days
Windows XP 64-Bit Edition is designed to address the most demanding needs of technical workstation users who require large amounts of memory and floating point performance in areas such as mechanical design and analysis, digital content creation and scientific and high-performance computing applications."
ntcompatible.com
