Internet Explorer 7 that comes with Windows Vista automatically defaults to using MSN as the search provider. Many users will want to use an alternative search engine such as Google or Yahoo.
You can easily change providers by loading IE7 and clicking on the small arrow to the right of the search box, then clicking "Find More Providers":
This will load a list of other large search engines, from which you can choose to make the default option (simply click on your choice):
This will bring up a dialog box asking you to confirm your selection. Tick the "Make this my default search provider" box and then click Replace Provider. This will make the search engine you have selected the default search engine for any queries performed in the IE7 search box.