There are numerous editors or IDEs that one can use for developing python programs.
On install, Python can be started easily by typing ‘python’ on the shell. On successful invocation of python a prompt >>> is displayed which can then be used to submit python commands/programs to python for running.
To exit this python shell, you can press Ctrl + z button and press Enter.
Active State’s python has a nice Python Editor that you can use to edit python programs. This editor also has a python shell where these programs are run. Moreover, this editor has a nice word auto-completion facility that can help you determine the possible attributes a module is exporting.
There are similar other python editors like UliPad (also provides a python shell), Crimson Editor, etc. Crimson editor is just a generic text editor much like TextPad and has no way to launch python shell for running programs.
The one IDE I like the most is Eclipse Ganymede. This is a generic SDK that can be complemented with PyDev Plug-in to enable Python and Jython editor. It comes with many goodies such as code completion, syntax highlighting, syntax analysis, refactor, debug and many others.
I use PythonWin or python shell alone for short test programs. For my run time environment, I prefer Eclipse
Python list of editors or IDEs is very long. Most of them are freeware / shareware.