Open registry editor by going to Start then Run and entering regedit and navigate to following three keys separately and change it as shown below:
[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main]
"Search Page"=" http://www.google.com"
"Search Bar"=" http://www.google.com/ie"
[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\SearchURL]
""=" http://www.google.com/keyword/%s"
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search]
"SearchAssistant"=" http://www.google.com/ie" .