I would like to suggest a website that is of tremendous assistance to students of Chinese. It has a basic English/Chinese dictionary in characters or Pinyin and will even provide audio pronunciation albeit rather limited in use. There are also many more features including the ability to type Pinyin and automatically include the tone marks. It is used by many schools and universities and it is free. I have been using it for some time and found it to be of considerable benefit.
It is http://www.mdbg.net/chindict/chindict.php
Good luck.....BH