Get Windows Version from Command line

Get OS version and Service Pack level of local machine:

systeminfo | findstr /B /C:"OS Name" /C:"OS Version"

Get OS Version and Service Pack level of remote machine:

systeminfo /s \\<REMOTE-HOSTNAME> | findstr /B /C:"OS Name" /C:"OS Version" 

Where <REMOTE-HOSTNAME> is the name of the remote computer.

Reference

http://www.windows-commandline.com/2009/01/find-windows-os-version-from-command.html