[ovirt-users] How many servers do I need to run oVirt?

Hello, sorry for a very basic question. But I searched the net for the basic answer and did not get it. How many servers do I need to run oVirt software? I understand I can access management GUI from anywhere on subnet but naming and they it is explained is confusing to me. I am planning to buy a bigger server (just one to use as compute host) with dual cpu and about 64GB RAM. I am thinking to run my webservers as VM on this proposed machine. I thought it was a level 1 hypervisor (then why does it say some places that I need CentOS or RH on my server?) I also have a FreeNAS server, I was thinking if it was possible to keep my VMs stored on there and run/load/execute them on this so-called-compute server. Will I have to build and keep my VMs (when powered down) on oVirt machine only? finally what will I loose in comparison to free vSphere, if I select oVirt? Thank you. Rajeev