It seems that the following is a common method given in many tutorials on switching a processor from 16-bit to 32-bit:

    mov     eax, cr0            ; set bit 0 in CR0-go to pmode
    or      eax, 1
    mov     cr0, eax

Why wouldn't I simply do the following:

    or      cr0, 1

Is there something I'm missing? Possibly the only thing I can think of is that I cannot perform an operation like this on the cr0 register.