I ran into this. It was another SAD STORY where the pirate had found some XP PRO 64-BIT version. There is no fix for them.
As I attempt to instal McAfee Anti-Virus software I receive a msg, "The version of Windows installed on this machine is not supported. Please refer to the products documentation for a list of supported operating systems". I was informed by McAfee that I need to uninstall XP, then remove ME and add XP back onto the system. Is there another fix, less complicated???
SP2 has already been installed and all other potenetial conflicting software has been removed (ie; ad-ware).