Apparently, it requires a 64-bit CPU but I wonder if really early 64-bit CPUs (e.g. 1st gen Intel Core) would work.
x64 has evolved quite dramatically since its inception.
Can you expound on this? Besides AES acceleration and virtualization support, I don't know of any features on modern x64 CPUs that would be a limiting factor in an OS that doesn't 'require' TPM support.