1. Type the following in the address bar:

[text]about:config[/text]

2. In the search field type:

[text]keyword[/text]

Result:
keyword.URL
keyword.enabled

3. Double-click “keyword.enabled” to be set to false.

4. Double-click the “keyword.URL” to set your source search engine:

Bing: http://www.bing.com/search?q

 

Restart Firefox and enjoy searching from the address bar!