Windows XP Professional x64 Edition is software, that was released on late April 2005. It is designed to run on x86-64 personal computers, and used to expand 64-bit memory address space from the x86-64. It came with two languages English, and Japanese. However, there was one unleaked version of the software in Russia.
The Russian Version
The Russian version had a screenshot from smojem.ru. It featured a screenshot of the desktop opening WIndows Media Player, System applet, and the Control Panel window open. It is unknown if a Russian version of the software is found or it's completely lost for decades.