TestDrive is an Ubuntu application that is especially designed for non-technical users to easily download and run the latest Ubuntu development daily snapshot in a virtual machine.

QEMU is a powerful, open-source machine emulator which allows you to run virtually any operating system inside your currently running distribution. In this brief tutorial I'll show how to run distributions for which the ISO is available, directly from within Debian or Ubuntu.

QEMU is a generic and open source machine emulator and virtualizer. When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances.

What is QEMU? It's a free software "processor emulator", which means it's capable of running applications written for other systems natively on your current operating system. The QEMU virtual CPU core library is released underneath the GNU LGPL. QEMU is capable of running a guest operating system on top of your current operating system, in the same manner as applications such as VirtualBox OSE and Vmware Workstation.

From Techthrob.com:

Virtualization is the technique of running a "guest" operating system inside an already-running OS; for example, Windows inside Linux, or visa-versa. This week Canonical, the company behind Ubuntu Linux, announced a partnership with Parallels, maker of the Virtualization products Parallels Workstation and Parallels Desktop for Mac. This article compares four virtualization products available for Ubuntu Linux: the free, open source Qemu; the closed-but-free versions of VirtualBox and VMware-Server, and the newly-available, commercial Parallels.

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