Cygwin is a Linux-like environment for Windows. It consists of two parts: A DLL (cygwin1.dll) which acts as a Linux API emulation layer providing substantial Linux API functionality, and a collection of tools, which provide Linux look and feel.
For additional information, please refer to: Cygwin: LSU Overview.
VirtualBox is a family of powerful x86 virtualization products for enterprise as well as home use. Not only is VirtualBox an extremely feature rich, high performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL). See "About VirtualBox" for an introduction; see "innotek" for more about our company.
For more information, see: VirtualBox: LSU Overview
Run virtual machines on your Windows or Linux PC with VMware Player. This free desktop virtualization software application makes it easy to operate any virtual machine created by VMware Workstation, VMware Server or VMware ESX Server, as well as Microsoft virtual machines and Symantec LiveState Recovery disks.
Linux Users: To download VMware Player, go to the VMWare Player download page and choose the bundle appropriate for your machine.