I understand iTextSharp can be used for converting a document to pdf.
But first we have to create a document from scratch using iTextSharp.text.Document and then add
Aspose.Words is indeed a good solution, but it doesn't offer perfect fidelity. At the time of writing it has problems with non Roman languages, complex formatting such as floating elements and a number of other problems.
You may want to have a look at this PDF Conversion Web Service that can be used from any Web Services capable environment including Java and .NET.
Note that I worked on this project so the usual disclaimers apply.