I once used open office ms wordOpenOffice for MS Word to pdfPDF conversion. Although it was the only free solution, I wasn't quite satisfied with the resulting pdfPDF file, specially when your documnetdocument has complex bidibidi scripts.
For conversion, as far as I can remember, there was two possible ways. One to use OS pipes and the other was socket or something. I don't have my code right now, but the only thing you need is to search in that URL. You should first launch an open officeOpenOffice executable file (I just followed a simple turorial in oo wikiOpenOffice wiki) with some parameters, and then run your javaJava application, using provided javaJava libraries.