Copy this to a text file and change the extension to .adm, then add it into your group policy in the realivent place.

 CLASS USER
CATEGORY !!WindowsComponents
CATEGORY !!InternetExplorer

POLICY !!PopulateSearchProviderList
#if version >= 4
SUPPORTED !!SUPPORTED_IE7
#endif
EXPLAIN !!IE_Explain_PopulateSearchProviderList
KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes”
VALUENAME Version
VALUEON NUMERIC 1
   ACTIONLISTON
KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes”
     VALUENAME DefaultScope VALUE “{2BC28A1E-D072-420F-9746-3CE8DC279237}”

KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes\{2BC28A1E-D072-420F-9746-3CE8DC279237}”
VALUENAME DisplayName  VALUE “Google”
VALUENAME URL               VALUE “http://www.google.co.uk/search?hl=en&q={searchTerms}&meta=”
END ACTIONLISTON
END POLICY
END CATEGORY
END CATEGORY

CLASS MACHINE
CATEGORY !!WindowsComponents
CATEGORY !!InternetExplorer
POLICY !!PopulateSearchProviderList
#if version >= 4
SUPPORTED !!SUPPORTED_IE7
#endif
EXPLAIN !!IE_Explain_PopulateSearchProviderList
KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes”
VALUENAME Version
VALUEON NUMERIC 1
   ACTIONLISTON
KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes”
     VALUENAME DefaultScope VALUE “{2BC28A1E-D072-420F-9746-3CE8DC279237}”

KEYNAME “Software\Policies\Microsoft\Internet Explorer\SearchScopes\{2BC28A1E-D072-420F-9746-3CE8DC279237}”
VALUENAME DisplayName  VALUE “Google”
VALUENAME URL               VALUE “http://www.google.co.uk/search?hl=en&q={searchTerms}&meta=”
END ACTIONLISTON
END POLICY
   END CATEGORY
END CATEGORY

[strings]
SUPPORTED_IE7=”At least Internet Explorer 7.0″
WindowsComponents=”Windows Components”
InternetExplorer=”Internet Explorer”
PopulateSearchProviderList=”Populate List of search providers”
IE_Explain_PopulateSearchProviderList=”This policy setting will allow you to populate a list of search providers that will be displayed in the Internet Explorer search box.\n\n If you enable this policy setting and if the “Restrict search providers to a specific list of search providers” Group Policy setting is enabled, this list will be the only list that appears in the Internet Explorer drop-down list. If the “Add a specific list of search providers to the user’s search provider list” Group Policy setting is enabled, this list will be added to the user’s list of search providers.\n\n If you disable this policy setting or do not configure it, users will have complete freedom to create their own search provider list.”