Maybe just a single option in the installer, "Make this the default version of Python", which is true by default, would be best. This could control file associations, App Paths, and anything else related.
[Martin v Loewis:]
Authoring new user interface interface is a tedious task. It is much easier to just have a public property, so you would have to install it as
msiexec.exe python2.4.0.msi DEFAULTPYTHON=1
Yes, but it's a tedious task undertaken by a single individual who knows something about how msi files work. Whereas a checkbox in the installer is easily understood by any user, including the vast majority who wouldn't know what "msi" meant, much less how to run execute one by hand with public properties specified.
Not that I'm going to complain about how you're handling this... after all, you're the one volunteering your time. But if you're interested in hearing random opinions from others, I am one who would find it awefully nice if the MS installer had an option to install a non-default version of Python. Then someday it would be much easier for me to keep around copies of Python 2.4, 2.4.1, 2.4.2, 2.5, 2.5.1, and 2.6 all on the same machine.
-- Michael Chermside