We are using Proxmox at work for hosting purposes. It's offering support for high availability, it's got a nice web console, you can clone VMs and all the lot of features. (And best of all: for non business use it's free of charge!)
Worth a try, Martin.
We're using Proxmox with both, Windows and Linux machines inside, and works excellent.
A couple of weeks ago a student here in our company was given the task to find out what's faster: VMWare ESX, Mircosoft HyperV and Proxmox.
The conclusion was: VMWare ESX is on the same level with Proxmox, performance wise and feature wise. Pricing was won by Proxmox though.
Microsoft HyperV is lacking features like cloning VMs. (You'd need the MUCH more expensive Windows Datacenterserver version in order to support cloning)
So.. all around the Proxmox thingy looks like a good choice if you don't want to spend a fortune to host VMs on a dedicated and headless machine. You'll get a good feature set paired with fair pricing. AND: You'll get it right away without paying for software lessons that people at VMWare see as mandatory. ; )