my book of knowledge says:
Using a Single Search Provider
To use a favorite search provider exclusively in the Search bar, follow these steps:
Click the Customize button on the Search bar.
In the Customize Search Settings dialog box, select Use One Search Service For All Searches.
Select a provider and click OK.
Searching from the Address Bar
Often the simplest way to search is to type a search string directly in the Address bar. For example, if you start typing something that Internet Explorer doesn't recognize as a URL.
Internet Explorer passes what you have typed to the current default Autosearch provider.
You can change the default Autosearch provider as follows:
Display the Search Explorer bar, using Classic Internet Search.
Click Customize.
In the Customize Search Settings dialog box, click Autosearch Settings.
In the Customize Autosearch Settings dialog box, select a search provider.
To change the behavior of the search provider (for example, to switch from showing a list of search hits to going straight to the most likely hit), choose an option from the When Searching list. The options available vary by provider.
hope this is what u wanted