Mac OS X 10.6: Changing the language shown in menus and messages
You can change the language shown in menus and messages in the Finder and in many applications. However, some applications can’t display their menus and messages in all languages.
To change the language:
Choose Apple menu > System Preferences, click Language & Text, and then click Language.
Drag the language you most want to see in menus and dialogs to the top of the list, and choose an option for sorted lists.
Languages list: If an application supports the first language in the list, its menus and messages will appear in that language. If it doesn’t support the first language, it will use the second language in the list, and so on. If you don’t see the language you want to use in the list, click Edit List.
Order for sorted lists: You can sort the items listed in a Finder window by name, date modified, size, and so on. The language you choose in this menu influences how the Finder sorts items by name.
These language settings may also change the language used in other parts of an application or in the text you see on some websites.