The article Changes in Word 2007 has been updated and republished on TechNet. It lists what's new, changed, and removed in Microsoft Office Word 2007 from Microsoft Office 2003.
If you are planning a migration to Word 2007, you’ll also find our ORK article Migration considerations for Word 2007 useful. For large file migrations, see Assessing your environment with the Office Migration Planning Manager.
For information about what has changed in other Office products, see Differences in the 2007 Office system.