Apart from the speed, I found the widget to be fairly accurate for French translation, and it was good with verb tenses where a lot of others usually choke. A good way to do it is to have an English-French (Spanish in your case) widget and a French-English widget both open. Copy and paste the French translation it gives you, and if it still makes sense after it translates it back into English then I'm usually confident with it.
Otherwise I used to use Google Translation.