Virtual Cluster using VirtualBox

I tested the new HPC Europa Milestone 6 DVD and created a virtual cluster using VirtualBox on my laptop. I created a head-node and two computing nodes connected via a VLAN.  The head node has two network interfaces, NAT which enables the connection to the outside world and an internal virtual interface. The two computing nodes have only one network interface each for the VLAN.
In picture number 1 the VirtualBox dashboard is shown with the 3 running computers

Picture number 1: The VirtualBox dashboard showing the 3 running computers of the virtual cluster

Picture number 2: The desktop of the head node (left) and the two computing nodes (right)

In picture number two a PBS job executing a simple MPI task is demonstrated. The head node is on the left and the two computing nodes are on the right.

My general impression is that this Virtual Cluster is an excellent tool for education where the teacher and later on the students can experience Parallel Processing using their own laptops fairly easily.