The other one that Jackie mentioned and I now use as my alternative spell-checker is GuruNet http://www.gurunet.com.

It can be installed on your computer so that you just right click on any word on a webpage (or bulletin board) whilst you are on line and it will search for a definition for you. There is also an option to search the web using a variety of search engines including the wonderful "google", mentioned above without having to open up another web browser page or losing your setting in AWAD.