I've tried many French-English automatic translation websites. Here I want to recommend one that has reliably helped me translate notes, emails and short passages from newspapers:
Translation.babylon.com has two windows to translate to and from French and English.
So, for example, if you are writing an email in French but are not sure if you got everything right, or have no time to look it up or check with a French speaker, just write it in English, copy-paste into the Babylon window and click translate. Copy-paste the French version.
Do the same for translating back from French.
It's okay for informal correspondence or quick reference, but when you write a serious formal letter in French, make sure it's checked and corrected by a knowledgable French speaker.