The virtualization environments QEMU and VMware can be used to boot the ParallelKnoppix live CD in a virtual machine. ParallelKnoppix provides a terminal server that allows compute nodes to be PXE booted over the network. The compute nodes can also be virtual machines. In this way, one can learn about parallel computing using a completely virtual cluster.
If bridged networking is used in the virtualization environment, real compute nodes can be booted from the virtual master node. A real HPC Linux cluster can be created in minutes, from any distribution of Linux, or from Windows.
The ParallelKnoppix homepage provides VMware virtual machines to set up a pre-configured 2 node virtual cluster. The virtual machines only need to be reverted, and the cluster is up and running in second. The master node can be easily be re-configured to use bridged networking, to allow creation of real clusters.
For more information, see the PK forum link on the homepage.