I was mistaken. Unlike previous versions, Office 2007 does allow users
to change the user interface language by purchasing and installing an
individual language pack or a multilanguage pack. See http://office.microsoft.com/en-us/suites/HA102113691033.aspx "Microsoft
Office Multi-Language Pack 2007 frequently asked questions". Individual
language packs are not available yet, but should be in a few months.