Microsoft Office 2007: change the user interface language

1. Click Start, click All Programs, click Microsoft Office, click Microsoft Office Tools, and then click Microsoft Office 2007 Language Settings.
2. Click the Display Language tab.
NOTE The Display Language tab is only visible after you install a Language Pack.
3. Select the language that you want to use for the Ribbon, menus, and dialog boxes from the Display Microsoft Office menus and dialog boxes in list.
4. Select the language that you want to use for Help from the Display Help inlist.
5. If you have three or more languages installed, the Display language priority order list is displayed. To change the language priority, select a language in the list, and then click Up or Down.
(http://office.microsoft.com)