I suppose you have MS Office 2007 on your system. If so, all you need is the free plugin from Microsoft that can do the job. You can get it from here. http://www.microsoft.com/downloads/details.aspx?FamilyId=4D951911-3E7E-4AE6-B059-A2E79ED87041&displaylang=en Code (markup):
or save docx to doc itself in newer versions of WORD and then we have plenty of pdf converters available in net
Shill for my blog but... Try Cute PDF & the Office 2007 file conveter if you need to open a docx and don't have Office 2007.
I think the free Add On for Microsoft Office 2007 i.e. XPS and PDF file saver is the best, it works like a charm and will also help in future works too.