R – Looking how to Implement Document Conversion in MOSS 2007

We've been tasked with creating a MOSS workflow that on it's final step will convert a document (most likely from word 2003 or 2007) to PDF and watermark it with the current date.

So far I haven't seen a definitive way to do this. Have looked at using the MS Word Interop dlls, but we will not be installing Word (or Office) onto the server – so that's really not doable. Another option I've looked at is using Aspose dll libraries for conversion.

From a topology standpoint, wondering if using one server exclusively for document conversion is a good way to implement this. (I've read some info that recommends this approach for larger organizations).

If anyone – who has preferable done this sort of thing, can give me some pointers or best practices on this I'd really appreciate it.

Thanks