Movable Python [
http://voidspace.org.uk/python/movpy/ ] is a portable Python development environment. It includes several free interpreters ( Python 2.2, 2.3, 2.4, 2.5, and Iron Python Production 1.0) and a dynamic Python interpreter (Movable IDLE,
http://voidspace.org.uk/python/movpy/movableidle.html ).
Apparently, there are plans to include into Movable Python the excellent freeware Python editor Stani's Python Editor (SPE,
https://sourceforge.net/projects/spe/ ), and support for enabling psyco (the Python pseudo-compiler,
http://psyco.sourceforge.net/ ).
Speaking of freeware Python IDEs, I've been using as of late PyScripter [
http://mmm-experts.com/Products.aspx?ProductId=4 ], which is a pretty good editor, with excellent auto-complete support. However, it crashes so often that it's almost useless. Now, I've been using it because Stani's Python Editor was hard to get (web page crashed), so I settled for a while. But
https://sourceforge.net/project/showfiles.php?group_id=145384 has now enough SPE distros to fit all taste, so good-bye PyScripter...
Finally, for more on Python IDEs, check: