There can be a problem with incompletely removed older versions. Vista saves some files to secret folders without telling the user or the program that they have been diverted. Apparently this is a security feature.
Python some pre-installed on Mac computers, but it is generally out of date. While this FAQ post may not answer the question, it just might. Here is some documentation for Mac users that might help them install the required Python and wxPython files. + Python for Mac: http://www.python.org/download/mac/ + wxPython for Mac: http://www.wxpython.org/download.php + Mercurial for Mac: http://mercurial.berkwood.com/
This FAQ is a public document. Anyone can add to it. So essentially the OpenRPG community is the maintainer of this FAQ. Tom Baleno a.k.a tdb30_ created the previous wiki form and incorporated information from the original FAQ created by Chris Blocher a.k.a. Heimdall. This version is maintained by the OpenRPG+ community.