That's ridiculous. An OS should come with everything it needs, to run optimally on all of the architectures it supports. Having a separate version is insane.
I guess that's one my reason why Microsoft is simply: horrible.
Lol, I usually agree that Microsoft sucks, but it's not them. They all have to have different versions because of the whole new architecture. New drivers, and new OS. It's like saying "Let me run this XBOX 360 OS on my computer.. oh wait its a different architecture." Now, the new x64 processors do have backwards compatibility for x86 (32-bit) so you don't have to change anything that you do now.