Another big problem is compatibility between AMD and Intel. AMD was the first who did 64 bit processors, so has created different registers and new instructions, the question is Intel will follow the standart created by AMD or create his own set as did with the extension to MMX, turning them useless for practical purposes. If the Cpu makers don't follow the same standart the 64 bit is dead, because it would need a Windows64 for AMD and a Windows64 for Intel, a Poser7 for AMD and other Poser7 for Intel, and so on.

Stupidity also evolves!