I've been trying to do a comparison of Parallels, VMWare & Virtualbox, but whenever I try to create a VM in Parallels, it tells me that my processor doesn't support hardware virtualization and refuses to create the VM. VMWare and Virtualbox both work fine, and Parallels let me install without a problem - but won't create a VM. Why is "hardware virtualization" necessary in Parallels - the others seem to work perfectly well without it. Is there a way to at least turn off or opt out of this requirement?