I found very good firefox plugin, which saved my time in translation some stuff. You can download it from here https://addons.mozilla.org/en-US/firefox/addon/918

The plugin is easy to use, you just highlight text then right click in popup window you see select Translation and see translated text. Besides, additional faeture is to insert text directly from textfield and texbox.

Available languages:

English to German / German to English
English to Spanish / Spanish to English
English to French / French to English
English to Italian / Italian to English
English to Portuguese / Portuguese to English
English to Japanese / Japanese to English
English to Korean / Korean to English
English to Chinese (Simplified and Traditional) /
Chinese (Simplified and Traditional) to English
English to Dutch / Dutch to English
English to Greek / Greek to English
English to Russian / Russian to English
Chinese (Simplified to Traditional) / Chinese (Traditional to Simplified)
German to French / French to German