A Unix shell can be obtained in Cygwin, a Unix compatibility layer used to compile Unix programs and run them on Windows. Microsoft also makes a shell known as "Windows PowerShell" which incorporates more Unix-like features than the standard command prompt.
You should be able to download the Unix Services for Windows, version 3.5, from Microsoft (free). There are other shell emulators that are available for Windows, which would allow you to use Unix type shell scripting without installing any additional OS. Your question about "virtual UNIX" is unclear ..
X Windows
x windows
A shell is a command interpreter. This is not limited to Unix. The programs COMMAND.COM or CMD.EXE are also shells in the DOS/Windows environments. The program EXPLORER.EXE is also a shell, though with a graphical interface.
There is no "default" Unix shell. Different Unix vendors shipped different shells.
The first shell was 'sh', the Bourne Shell
The a default Unix shell is the shell that comes with and is activated initially with your distribution of Unix. The shell is essentially the program the runs the command line interface allowing someone to interact with their computer. Some examples are the Bourne-Again shell (bash) or the Bourne shell (sh).
Mac OS X is an operating system running a UNIX shell, unlike Windows which uses a DOS shell. Most software must be specifically designed for use on Mac OS X because of its different shell, though UNIX provides Mac with improved security.
Because Linux evolved from UNIX, but Windows evolved from DOS.
The Korn shell.
Since there isn't a UNIX 95 or UNIX 98 per se, I think you are referring to Windows 95 or Windows 98..
tHE QUESTION WAS WHAT IS THE DIFFERENCE BETEEN unix and windows 7, but i did not get the appropriate answer.