There are a few methods of running virtual machines on a Linux host: VirtualBox, VMWare, KVM, and QEMU are four of the most popular. Each method has it’s pros and cons. More here

This tool is an easy to use graphical front end for the QEMU virtual machine tool. In this tutorial you are going to learn how to create a virtual machine using QTEMU. But why use QTEMU? QTEMU will work as a front end for either QEMU or KVM. So if you have the hardware to support KVM you can go that route and have a much more efficient virtual machine.