At the top right of the Internet Explorer 7 window is the search bar which enables you to perform a search against your favorite search engine. However, by default, only Microsoft's own "Live" service is configured.
So to add you own search providers, follow these easy steps:
Click the "Down Arrow" icon next to the Search bar and choose "Find More Providers". This will take you to a Microsoft Web Page that Microsoft has supplied additional Search Providers to choose from.
From this Web Page click on the Hyperlink for the Search Provider you wish to configure (eg. Google) and it will ask you whether you want to add it to your list of search providers. To do so, click the Add Provider button. If you like, you can also check the box to make this new provider the default search engine.
If you would like to change your default search provider to another one (assuming you have more than 1 already configured), click the "Down Arrow" icon next to the Search bar and choose "Change Search Defaults".
From this list you can select the Search Provider that you'd like to be the default and click on the "Set Default" button.