http://www.activestate.com/ they provide avtivepearl. It's no problem to install it.
http://www.ruby-lang.org/en/ there you get ruby. They provide a link to the "one click ruby installer" which you will find here: http://rubyinstaller.rubyforge.org/wiki/wiki.pl there is the
I'v had downloaded already Perl from activestate, and I believe I came across the ruby installer you mentioned but didn't installed it yet...
after installing you should check if the *.exe of perl and ruby is in the default path. you can easily check in the command line by calling ruby --version and perl --version
To get the context scripts running they should also be in the default path (this given path is valid for my miktex installation, you probably have to change it)! C:\texmf\scripts\context\perl C:\texmf\scripts\context\ruby
I had to add them manually.
Thanks for you information... Pragma site also mentions ghostscript, is it realy needed or only if you want postscripts ? Once again thank you, Miguel Queirós