Please make sure that you use a regular Python 2.x release (v2.4 or above).
Python 3.0 is currently not supported.

Execute python -V in a console to get the installed Python version.

After your successful Python installation, you need to add the installation folder to the so-called PATH environment variable, which contains a list of directories that are searched for executables.

Suppose you installed Python to its default location C:\Python26, open a Windows command shell (choose menu Start → Run… and type cmd). The following command prepends the installation folder to the value of PATH, separated by a semicolon:

set PATH=C:\Python26;%PATH%

When you now execute python -V, it should print out its version number.

The modification of the PATH variable as described above is only temporary. In order not to repeat the command each time you open a new command shell, modify the PATH variable permanently: in Start → Preferences → System choose Environment variables under the Advanced tab. Edit the system variable Path by prepending C:\Python26;.

In a standard Python installation on Windows, the .py file extension gets associated with the Python interpreter. This allows you to invoke .py files directly. You can check that in the following way at a command prompt:

C:\>assoc .py
.py=Python.File

If this doesn't work, you can add a file association through Windows Explorer → Extras → Folder Options → File Types.

If for any reason you cannot use a file association for .py files, you can still invoke the Python interpreter directly, passing the original command line as arguments. In this case, make sure to provide a path prefix for the script name, even for scripts in the same directory, like so (this will be fixed later):

python ./generate.py source

To run qooxdoo's Python-based tools without problems, it is important to have Python installed as an administrator "for all" users.

Administrators installing Python "for all" users on Windows Vista either need to be logged in as user Administrator, or use the runas command, as in:

runas /user:Administrator "msiexec /i <path>\<file>.msi"

Older Macs (e.g. 10.4) may need an update of the pre-installed Python. See the following comment from the Python on Mac page:
"Python comes pre-installed on Mac OS X, but due to Apple's release cycle, it's often one or even two years old. The overwhelming recommendation of the "MacPython" community is to upgrade your Python by downloading and installing a newer version from the Python standard release page."