I started looking at VM’s (Virtual Machines) again and read this nice review on GnomeBoxes, an opensource VM tool. It only runs on Linux/Gnome, but it seems very easy to use. Downside, it runs only on Linux, and it doesn’t seem as feature rich as VirtualBox.
http://www.makeuseof.com/tag/gnome-boxes-easy-way-set-virtual-machines-linux/