Oracle VM VirtualBox 4.3.24
                 https://www.virtualbox.org

Oracle VirtualBox (formerly Sun VirtualBox, innotek VirtualBox and Sun xVM VirtualBox) is a free and cross-platform virtualization application that provides a family of powerful x86 virtualization tools designed for desktop, server and embedded use. VirtualBox can be used on Linux, Solaris, Mac OS X and Microsoft Windows platforms to run virtual machines of any of the aforementioned operating systems, as well as any BSD distribution, IMB OS/2 flavors, DOS, Netware, L4, QNX, and JRockitVE.
It's portable

Oracle VirtualBox is portable, requires no hardware virtualization, includes guest additions and great hardware support. It also features USB device support, full ACPI support, multiscreen resolutions, and built-in iSCSI support. Support for PXE network boot, multigeneration branched snapshots, remote machine display, extensible RDP authentication, and USB over RDP (Remote Desktop Protocol) is also integrated in Oracle VirtualBox