Oracle - (Open Source)
VirtualBox is an easy and elegant solution for those who want to control a computer from another computer.
 VirtualBox offers virtualize your operating system (OS) guests on a host machine. Called hypervisor, the application supports Windows OS X, Linux, Mac, Solaris, FreeBSD, etc.. as host, Mac OS X missing the call as a guest. 
 
 It also includes a remote access via HTTP protocol, convenient for demonstrations on a clean system. The ability to manage multiple states of the system is particularly interesting and its interface is very simple.
 
 Virtualization solutions allow installing an operating system on a virtual machine using the resources of the host PC , thus enjoying very good performance. In the genre, several solutions are known for their ease of use, such as VMware Workstation , Parallels Desktop or Microsoft Virtual PC 2007 SP1. 
 
 A virtual machine is a useful way to use two operating systems simultaneously and harmless to the host computer. There is the possibility to install Linux on a virtual machine on Windows and vice versa . 
 This is a maintenance release. The following items were fixed and/or added:
 * GUI: fixed a bug which prevented to add more than one SATA drive from the GUI
 * GUI: fixed a regression introduced in 1.6.0: the fullscreen mode was left on every guest video mode switch
 * GUI: fixed several minor issues
 * Networking: fixed a host interface networking regression introduced in 1.6.0
 * VMM: fixed starting of VMs with AMD-V enabled
 * VMM: massive performance enhancements for AMD-V
 * VMM: stability improvements for AMD-V on Windows hosts
 * VMM: correctly detect AMD CPUs with erratum 170 (AMD-V)
 * VMM: detect inconsistent timestamp counters on certain AMD Phenom CPUs (Windows host only)
 * VMM: fixed KVM check (Linux hosts only) XPCOM: fixed several races
 * VMM: xed a regression introduced in 1.6.0: Windows stuck during installation
 * SATA: improved performance with Vista guests
 * SATA: fixed statistics counter
 * Shared Folders: several fixes (iTunes download, speed up browsing)
 * ATA/IDE: fixed boot from CDROM if a medium was added while the boot menu was active
 * Networking: provide an Intel PRO/1000 T Server (82543GC) network device emulation which is recognized by Windows XP guests
 * Networking: fixes for the E1000 emulation (don't crash if not attached, fixed a bug in the statistics counter implementation)
 * NAT: don't crash if the guest sent a DHCPRELEASE message with an invalid IP address
 * NAT: fixed ARP reply for the NAT gateway and for the NAT name server if the guest IP range was changed
 * Internal Networking: fixed shutdown if more than two VMs are connected to the same network
 * BIOS: allow to change the DMI informatiton (see chapter 9.13, Con'guring the BIOS DMI information, page 125)
 * RTC: fixed UIP emulation to prevent jumping of time in Solaris guests
 * Windows host: VirtualBox installation directory corrected for 64 bits Windows
 * Windows host: fixed VBoxVRDP.exe symlink
 * Windows host: solved locking problems in raw partition VMDK support
 * Windows host: fixed stability during high system load (page fault in KeQueryActiveProcessors)
 * MacOS X host: fixed crashes under certain conditions
 * Shared Folders: limited users without admin rights now also can use Shared Folders on Windows guests
 * Linux hosts: fixed default runlevel for the kernel module helper script
 * Solaris hosts: enabled support for VT-x and AMD-V
 * Solaris hosts: dynamic loading of libdlpi fixes a problem where Solaris 10 was not able to start a VM
 * Linux additions: fixed runlevels for kernel module helper scripts
 * Linux additions: compatibility fixes with Linux 2.6.26
 * Linux additions: fixed occasional guest kernel crash during unload of the vboxadd guest kernel module