Some but not all. If you buy a Dell 2950 quad and load it up with 8 Gig. You
can spend $500 on an ESX 3i license and run 10 - 15 512 MB OpenBSD single
processor VMs. The difference here is that you can max out the duty cycle
on the box where as a single OS running on the same Iron won't do that. For
ESX it's designed for you to max out the hardware