In Touch with Dynamics (GP) looks at upgrade issues around Emailing POs using new GP2010 word templates.
I would add that Office needs to be the 32 bit version to email Word templates.
In Touch with Dynamics (GP): Emailing POs using new GP2010 word templates
Excel & OfficeGP 2010
Archived post from 2011. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.