To clear the search box on google.com or the history of any text box:

1. Select "Internet Options" from the Internet Explorer "Tools" menu.
2. Select the "Content" tab at the top of the "Internet Options" window.
3. In the "Personal information" section at the bottom, click the "AutoComplete" button.
4. On the AutoComplete Settings window, click on the "Clear Forms" button.
5. You will get a window asking you to confirm clearing the history.
6. Click "OK", and you're done.

Note: This is confirmed for use with Internet Explorer, but not MSN Explorer (Allan)