> Old quad core won't have all the virtualisation extensions.

Intel's first quad core was Kentsfield in 2006. It supports VT-x. AMD's first quad core likewise supports AMD-V. The newer virtualization extensions mostly just improve performance a little or do things you probably won't use anyway like SR-IOV.

Ivy Bridge is 13 years old today. You need to do the the things to buy something older than that in 2025.

Virtualization existed long before virtualization instructions. Not strictly necessary.

An old Xeon then.