I just spent several hours getting a reasonable python environment working under Windows, something I had hoped to never have a need for. The Buildbot is having some.. disagreements.. with Windows, and it became clear that being able to reproduce the problem locally was the only sane way to fix it.

Man, was that painful.

For the record, here's what I did. Many thanks to Bear for creating this checklist and walking me through the process:

0. Check to make sure your PATHEXT environment variable has ";.PY" in
it -- if not set your global environment to include it.

 Control Panels / System / Advanced / Environment Variables / System variables

1. Install python -- 2.4 -- http://python.org
       * run win32 installer - no special options needed so far

2. install zope interface package -- 3.0.1final --
http://www.zope.org/Products/ZopeInterface
       * run win32 installer - it should auto-detect your python 2.4
          installation

3. python for windows extensions -- build 203 --
http://pywin32.sourceforge.net/
       * run win32 installer - it should auto-detect your python 2.4
          installation

 the installer complains about a missing DLL. Download mfc71.dll from the
 site mentioned in the warning
 (http://starship.python.net/crew/mhammond/win32/) and move it into
 c:\Python24\DLLs

4. at this point, to preserve my own sanity, I grabbed cygwin.com's setup.exe
   and started it. It behaves a lot like dselect. I installed bash and other
   tools (but *not* python). I added C:\cygwin\bin to PATH, allowing me to
   use tar, md5sum, cvs, all the usual stuff. I also installed emacs, going
   from the notes at http://www.gnu.org/software/emacs/windows/ntemacs.html .
   Their FAQ at http://www.gnu.org/software/emacs/windows/faq3.html#install
   has a note on how to swap CapsLock and Control.

 I also modified PATH (in the same place as PATHEXT) to include C:\Python24
 and C:\Python24\Scripts . This will allow 'python' and (eventually) 'trial'
 to work in a regular command shell.

5. twisted -- 2.0 -- http://twistedmatrix.com/projects/core/
       * unpack tarball and run
               python setup.py install
       Note: if you want to test your setup - run:
               python c:\python24\Scripts\trial.py -o -R twisted
       (the -o will format the output for console and the "-R twisted" will
         recursively run all unit tests)

 I had to edit Twisted (core)'s setup.py, to make detectExtensions() return
 an empty list before running builder._compile_helper(). Apparently the test
 it uses to detect if the (optional) C modules can be compiled causes the
 install process to simply quit without actually installing anything.

 I installed several packages: core, Lore, Mail, Web, and Words. They all got
 copied to C:\Python24\Lib\site-packages\

 At this point

   trial --version

 works, so 'trial -o -R twisted' will run the Twisted test suite. Note that
 this is not necessarily setting PYTHONPATH, so it may be running the test
 suite that was installed, not the one in the current directory.

6. I used CVS to grab a copy of the latest Buildbot sources. To run the
   tests, you must first add the buildbot directory to PYTHONPATH. Windows
   does not appear to have a Bourne-shell-style syntax to set a variable just
   for a single command, so you have to set it once and remember it will
   affect all commands for the lifetime of that shell session.

  set PYTHONPATH=.
  trial -o -r win32 buildbot.test

 To run against both buildbot-CVS and, say, Twisted-SVN, do:

  set PYTHONPATH=.;C:\path to\Twisted-SVN