I was running an amd64 build of Ubuntu on a VM on a Windows host which was also amd64. Later I found I could not run the same amd64 iso on my laptop, which is intel without hyper-V. I was confused I thought chipset mattered, but maybe it does not.

When buying a PC or Apple, is there anything to check about the chipset to make sure it can run different types of VMs?

In my case, I was trying to run ubuntu on a Thinkpad T520. Per answer below, I did need to enable some bios settings. I'm still having some issues. Running ubuntu on virtual box, when I try to use ubuntu-12.10-server-amd64.iso for the CD/DVD device to start a new VM, virtualbox complains "Failed to open the CD/DVD image . Could not get the storage format of the medium (VERR_NOT_SUPPORTED). When I try to use ubuntu-12.10-server-i386.iso the ISO is accepted, but then the VM complains "FATAL: No bootable medium found! System halted."

I had been using an amd64 iso on my home PC which is amd64 and it works fine, which is why I suspected CPU mismatch was the problem at first. But it seems like I'm having issues, and maybe this superuser thread can be used to verify the cpu is irrelevant in this case.