Windows Live Messenger Translator is a Social & Communication software developed by Senstic. After our trial and test, the software is proved to be official, secure and free. Here is the official description for Windows Live Messenger Translator:

Edit by Marydown: Windows Live Messenger Translator is provided here for FREE as an open source project. You are welcome to download it, use it, or Improve it as you wish.

Features
Translate between English, Arabic, Bulgarian, Chinese, Croatian, Czech, Danish, Dutch, Finnish, French, German, Greek, Italian, Japanese, Korean, Norwegian, Polish, Portuguese, Romanian, Russian, Spanish, Swedish.
Instant translations as you type in your instance messages.
Translate both incoming and outgoing IM text.
Translation is done via Google Translation Service.