VirtualBox 4.3.20.96996 Final + Extension Pack

VirtualBox - a special program to create a memory PC virtual machines. Each virtual machine can contain an arbitrary set of virtual devices and a separate operating system. Scope of virtual machines is very wide - from performing the functions of software testing to create entire networks, which are easily scaled, load-balance and protect. VirtualBox is free, open source software.

Extension Pack adds the following features:
The virtual USB 2.0 (EHCI) device; see the section called "USB settings".
VirtualBox Remote Desktop Protocol (VRDP) support; see the section called "Remote display (VRDP support)".
Intel PXE boot ROM with support for the E1000 network card.
Experimental support for PCI passthrough on Linux hosts; see the section called "PCI passthrough".

Setting:
Start VirtualBox, go to the File menu "Settings" Plug-ins and add the downloaded files with extensions .vbox-extpack
Additional Information:
There are versions of VirtualBox, intended for installation on virtually all operating systems, including Windows, Linux, Macintosh and OpenSolaris. As a "guest" operating system can also be used in any operating system, including Windows (NT 4.0, 2000, XP, Server 2003, Vista, W7), DOS / Windows 3.x, Linux, and OpenBSD.

Main Features:
VirtualBox can run as a GUI-interface or through command line.
To expand the functions of the program, a special set of SDK.
Parameters of virtual machines are described in XML format and does not depend on the physical computer on which the system operates. Therefore VMs format VirtalBox easily transferred from one PC to another.
When using the "guest" computer operating systems, Windows or Linux, you can use special tools which substantially facilitate switching between the physical and virtual computers.
For the rapid exchange of files between the guest and the physical PC, you can create so-called "shared folders" (Shared folders), which are simultaneously accessible from both of these machines.
VirtualBox allows you to connect USB-devices to virtual machines, allowing virtual machines to work with them directly.
VirtualBox fully supports the remote access RDP (Remote Desktop Protocol). The virtual machine can run as RDP-server, allowing you to manage it remotely.

What's new:
https://www.virtualbox.org/wiki/Changelog