Here there are many tools you will find in website while searching for word to pdf converter. But I found very few people who know the official Microsoft Office tools to convert word file to PDF. You just need to download a extension of Microsoft Office of only few kilobytes (kb) and install it. Now you will find a option in MS office "Save as PDF" same as Save As doc, docx etc. Thats it.
Download link: 2007 Microsoft Office Add-in: Microsoft Save as PDF
File Size: 915kb
Open a word file with MS Office
Click the Office button
Scroll to save as and then PDF. Click PDF