Virtualization

ESXI is a hypervisor (an OS that supports running VMs). Up to a certain point it is free (# of sockets and amount of RAM), but if you start using it for production you'll likely need enterprise licensing. We have a test box here that's a 2nd Gen i7 with 16GB of RAM that contains a virtual lab with 8 VMs in it. It's our test environment for software deployments and configuration changes.

I'm not sure what your question is, but here is info on ESX: http://www.vmware.com/products/vsphere/esxi-and-esx/index.html