Citrix XenServer is easy and free!
Just for grins, I loaded XenServer the other day. It was *REALLY* easy. No big surprises, get the installers for XenServer and XenCenter. Load XenServer on the server you are going to use for a hypervisor host. Load XenCenter on any old Windows machine. You have to register for a free license, and then install it.
Compared to a vSphere and vCenter install, it was very simple and easy.
It seems to work well, too.