innotek's VirtualBox is an x86 virtualizer for Linux, Mac OS X, and Windows 32-bit and 64-bit hosts. It can run FreeBSD, Linux, OpenBSD, OS/2 Warp and Windows as unmodified guest operating systems. It comes in a closed-source edition and a free-of-cost GPL edition. The closed-source enterprise version is free for personal use and evaluation; enterprise users can purchase support licenses. The enterprise edition includes some features not present in the GPL version:
- RDP (Remote Display Protocol) to connect to any RDP client on your virtual machines
- iSCSI support
- Full USB support, including USB over RDP for RDP clients
VirtualBox has gone from being unknown to being popular in a short time. It's especially nice for running Windows on top of Linux because it delivers good, peppy performance. It supports hardware virtualization (Intel's VT-x and AMD's AMD-V), but the maintainers recommend not enabling this because VirtualBox is faster without it.
It's easy to test this for yourself, as enabling and disabling hardware virtualization takes just a couple of mouse clicks. VirtualBox's hardware support is excellent it supports PXE network booting, multiple screen resolutions and ACPI power management. In addition, VirtualBox offers the ability to take snapshots of your virtual machines, so you can roll back in time, as well as the ability to share files on the host system with Linux and Windows guests.
The easy way to try VirtualBox out is to use Debian or one of its derivatives, such as Mepis or Kubuntu. It's included as a standard Debian package. It comes with some good graphical administration tools, so setting up and configuring new virtual machines is pretty easy. VirtualBox's overall polish and ease-of-use put it ahead of most other virtualizers. Visit VirtualBox.org for downloads and much good documentation.