In Python 3.3 there's a new option for automatically adding Python to
PATH environment variable.
Besides using the automatically created start menu entry for the
Python interpreter, you might want to start Python in the command
prompt. As of Python 3.3, the installer has an option to set that up
At the “Customize Python 3.3” screen, an option called “Add python.exe
to search path” can be enabled to have the installer place your
installation into the %PATH%. This allows you to type python to run
the interpreter. Thus, you can also execute your scripts with command
line options, see Command line documentation.
However Python's installer on Windows by default associates Python files with Python interpreter so users can run Python scripts just by clicking Python script or a link to it.