Transmiti is a Google Powered portable apps which can translate text from any application text editors, browsers, Firefox, Opera, chrome, Messengers (yahoo and MSN) etc.
Very easy to translate just highlight the desired text and click the Windows key. It will provide a pop-up window with the translation. You can also set the replaced option which is located in settings after this option text will be replaced with the translated text (your desired Language).
Transmiti works on Windows XP, Windows Vista and Windows 7.
Transmiti can also used with browsers and the procedure for translating text is almost the same as for desktop apps.