A window, as in the glass viewing panel, is physical and let's you see through it. Microsoft Windows is a software package that is data based. You can't look through Software.
You can install Windows without a product key and it will work for x amount of days before forcing you to enter your product key. Each version of Windows has its own rules and can work for longer...
The computer name that comes up on the Network is the one that was configured in the system properties. You can reconfigure the Computer name by going to: :: Windows XP :: My Computer >> Right...