“Perl Script “MSI” Installer” should, of course, read “Python Script “MSI” Installer”. (Sorry to all the Python aficionados out there; my Perl roots are showing.)
Speaking of Perl, if that’s your scripting language of choice, installing Text::Markdown will install markdown.pl and markdown.bat (genererally into ...\site\bin\markdown.bat or similar). If you don’t have the Python standalone executable, but do have Perl, you can change the Preview HTML filter definition for Markdown to
[Markdown]
Extension=.md .markdown
Language=Markdown
Command=markdown.bat "%1"
If your various perl bin directories aren’t in your path, you will need to use the full path to those directories (such as Command=\strawberry\perl\site\bin\markdown.bat "%1").
If you use extensions beyond the original daringfireball syntax in your markdown, you will probably want Text::MultiMarkdown with its associated multimarkdown.pl/multimarkdown.bat for your filter, instead.