Here's a question that I get from time to time...
Q: How do I install speech recognition for a language other than the language Windows Vista is running in?
A: By installing a language pack.
Language packs are the Windows way of installing additional language support for features included in the OS. By default, when you install Windows Vista (or purchase a PC with Windows Vista already on it), it comes with a single language.
In Windows Vista Enterprise and Windows Vista Ultimate, you can go to the control panel, search for "display language", and then click on the "Install or uninstall display languages" link.
Follow the on-screen instructions, and in no time you'll have additional recognizer languages as long as it's a Windows Speech Recognition supported language. In Windows Vista we support US English, UK English, German, French, Spanish, Japanese, Simplified Chinese, and Traditional Chinese.