Using Hazel or AppleScript to Convert Word to PDF
This AppleScript should do what you want:

https://discussions.apple.com/message/15180576#15180576

You would need to have Word running, however, for this to work. It's not my code but I just tried it out as a service in Automator with 10.9 and Office 2011 and it works both with a single and multiple Word docs.

I suppose using the actual Word app is the only way to ensure correct layout but using a command-line Word-to-PDF converter could be done, too.