If you have Acrobat Standard or Professional installed Adobe PDFMaker is available.
Use it to convert the Word file to PDF.
As there are specific "bands of compatibility" vis-a-vis an Office release and an Acrobat release you do want to ensure that the version of Acrobat used is compatible with the version of Office installed.
Properly configured (via the settings under the different tabs in the dialog) , Adobe PDFMaker will convert the Word file to a Tagged output PDF with the active links.
Tagged output PDF is needed for PDF ebooks that are to be used on eReaders as this facility is what supports reflow (needed for the smaller screen size, eh).
Oh yes, smaller, appropriate page size helps too (but I'd guess you've got that already).
Regarding Acrobat (PDFMaker) compatibility ... See:
TechNote ID 333504 –
Acrobat PDF-capable web browsers and PDFMaker-compatible applications (Acrobat 6.x - 9.x on Windows and Mac OS)
Joel Geraci's blog article –
Version Compatibility of Acrobat PDFMakers
In addition to the Word-Version / Acrobat-Version matchup, Acrobat (9 Pro Extended) cannot bring links, internal to the document, into a PDF file if the document is set up with more than one page per sheet (Word 2003). If you try, you will get an error message telling you that.