I think a 3rd party can help to solve it.
What about use Development. Please take a look.
Have a look at the
PDF Converter for SharePoint. It allows PDF documents to be created for most popular formats including Word and InfoPath.
Conversions can be controlled via
automated workflows or from your own code using
Web Service calls.
yes you can conveet doc fil to pdf file in moss2007 by using MossDocumentConverter a third party tool need to be installed :
find here :http://docconverter.codeplex.com/