Note that this is not the same as translation -- it is the sound of the words that is converted from one alphabet to the other, not their meaning. Converted content will always be in Unicode.
Google Transliteration IME is currently available for 22 different languages - Amharic, Arabic, Bengali, Farsi (Persian), Hebrew, Hindi, Kannada, Malayalam, Marathi, Nepali, Oriya, Punjabi, Greek, Gujarati, Russian, Sanskrit, Serbian, Sinhalese, Tamil, Telugu, Tigrinya and Urdu.
To close IME, you can change the language in language bar or try right clicking on the current application to see whether it supports 'Close IME' popup menu option or by closing the current application.
If you want to use IME with any application like notepad, you must first open the application and then open our IME. IME can be opened by clicking on the language bar on the desktop and then selecting the IME language icon or through a shortcut key if it's already configured.