How to change the OS X system language
Like most operating systems, OS X supports multiple languages, with full character sets and fonts for practically every language. In addition, there is full localization for a number of these languages, so you can have the system display menus and other system features in the language of your choice.
To do this, open the Language & Text system preferences, and in the Language tab drag the language you would prefer to the top of the list. After a restart, your system and applications will use that language, if they include localization support for it. Be aware of that qualifier because … Read more