Firefox 3.6 - Navigation Toolbar - Google search box language
Solution 1:
The Add to search bar extension will do this for you.
Solution 2:
Just to add to this i have found this link...
http://www.howtogeek.com/howto/15127/make-firefox-show-google-results-for-default-address-bar-searches/
which makes it even easier to do a google search in the address bar. It essentially removes the default 'I feel lucky' search within the firefox address bar and thus brings up the results in a normal google search page.