Dual core processors with virtualization

Hi all,

I was interested in finding out if anyone has detailed info on dual core processors with virtualization instructions enabled, tested against an optimized hypervisor for said instructions (like Xen, or VMWare or others).

In short, I'm looking for a good plateau to upgrade my web server and make it even more overkill, with a dual core system, but run the OS on a hypervisor so I can run more than one OS for a variety of reasons.

I realize you can do that now, but without the hypervisor, existing VM solutions are rather heavy on the overhead, if you need to run at least one Windows server. Btw, the mention of a Windows server was not an invite to flame, just a fact of life for my existing needs

Thanks ahead,

John