I found this in a few different places around the 'net - hopefully it's helpful:

Search for Information From the Address Bar in Internet Explorer

You can quickly search for information on the Web using the AutoSearch feature in Internet Explorer 6 in Windows XP:

• In the Address bar, simply type "go" or "find" or "?" followed by a keyword or phrase, and then press ENTER. Your search results will soon appear.

Note Internet Explorer searches for your word or topic using only one search service. If you don't find what you need, click the Search button on the toolbar and try using different search services.