I specifically asked how to change the search provider in the taskbar address toolbar, not in IE itself. These are not the same thing. Both above answers therefore, however well intentioned, addressed the wrong question. However, in the interim it occurred to me to seach the registry for 'Yahoo', and as a result of this and other research I am now in the position to answer my own question. Go to the following registry key: HKEY_CURRENT_USER\Software\DeviceVM\Browser Configuration Utility\IE. Change the AddressBarSearchName to Google and the AddressBarSearchURL to "
{searchTerms} - Google Search=" (minus the quotes). And there you have it.