There are many different ways to run a virtual machine in Linux.
The native way is to use zen, which is the option in PCC. However, it is complicated, still (I think) experimental, needs a lot of kernel knowledge and is generally difficult to understand. (Just my opinion.)
VirtualBox and VMware are two commercial applications which allow virtual machines to be run. VirtualBox has an open source edition which is in the repository. They are much easier to use.
You don't need more than one unless you really want to experiment with them.
If there is a zen expert here they will be able to explain it better.