If you wish to use Inquisit's speech recognition capabilities on Windows XP, you'll need the Microsoft Speech Engine 5.1 (or a compatible alternative), which you can download below. If you are running Windows Vista or later you do not need to download these components because they are included by Windows.
Microsoft ships the engine in 3 different languages packs; English, Japanese, and Chinese. Importantly, each package installs the exact same language neutral speech engine, so you can use any of the packages to process speech in any Windows-supported language. The language of the package refers only to the user interface of the control panels and wizards that allow you to configure the engine. If you install the Chinese version, for example, you can still use the engine to process German speech. However, the labels and instructions on the Microphone Wizard and other speech wizards would be written in Chinese.
Download Microsoft Speech 5.1 (English)