High Quality Content by WIKIPEDIA articles! Win4Lin was a proprietary software application for Linux which allows users to run a copy of Microsoft Windows 95, 98, Me, 2000 or XP applications on their desktop. The system works by acting in a similar way to a virtual machine, in that it provides an environment for the Windows operating system to run, and as such one must still have a copy of Windows to use with it. The Win4Lin application in essence displays a window on a Linux desktop which contains the Windows desktop environment. As an alternative, the Windows environment can be run full screen, outside of the desktop environment to save on desktop real estate.