The change between Firefox 3.6.* and Firefox 4 is how location bar search works. In Firefox 3.6 it uses Google "Browse by name" search. With the browse by name search, it performs a Google search and if there is a clear match it will take you to the site, otherwise it shows the Google search result. With Firefox 4 it just performs a Google search if you type something which is not recognised as a URL.

To get the Firefox 3.6 behaviour on Firefox 4 you need to change a hidden preference.

1. Type about:config into the location bar and press enter
2. Accept the warning message that appears, you will be taken to a list of preferences
3. Locate the preference keyword.URL, double-click on it and change its value to the link shown below

http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q=

Thanks for the response. The link does not take me anywhere but to either igoogle in IE or Google's main page in Firefox. But, I figured out where you were going and it worked. Thanks for your help.

so how do you do it again ? i did what TonyE said but didn't work too

Type about:config into the location bar and press enter

   Accept the warning message that appears, you will be taken to a list of preferences
   Locate the preference keyword.URL, double-click on it and change its value to:

http://www.google.com/search?btnI=I%27m+Feeling+Lucky&ie=UTF-8&oe=UTF-8&q=

If you prefer, you can also do this by installing the Browse by Name extension - https://addons.mozilla.org/firefox/addon/browse-by-name

awesome, thanks for clearing that up