In Office 2010, the export to PDF is included out-of-the-box simply via the Save as feature.
That’s nice and neat, but be aware that by default, the resulting PDF is enhanced by accessibility tags. These tags may result in unwanted tooltip windows on hovering an image in Adobe Reader:
You can overcome this by invoking the Options dialog directly from the Save as dialog:
Here you can deselect the corresponding option:
Unfortunately this has to be done before every export.