Change Firefox Address Bar Search Engine

If you, like me, has been the victim of Yahoo Spyware aka Yahoo IM then you may notice that in the firefox location bar if you type in a keyword, it takes you to Yahoo preferences page. Previously it used to perform a Google "I'm Lucky" Search and take you to the first page of its search results automatically.

If you want to restore the Google "I'm Lucky" search then perform this simple steps:
1. Type about:config in Firefox location bar and press Enter
2. Type keyword in Filter textbox and you will see only the preference keyword.URL.
3. Double-click on keyword.URL and change the value to:
http://www.google.com/search?btnI=I%27m+Feeling+Lucky&q=
or, if you don't wish to go to the first suggested link by Google
http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&q=

That's all it takes to restore default keyword search functionality in Google.

Note: You can use this to change to any search engine for keyword search.