On second thoughts, I've renamed this to be a general-purpose thread for discussion on IE 7.0 Beta 1.
Using it as my primary browser during the beta test period so that I'm in a better position to report issues and provide feedback. So here's the first little tweak - you'll notice that the search bar doesn't include the option to add additional search engines. The option is there, it's just not exposed in Beta 1.
To add additional search engines (Dictionary.com for this example), fire up the Regedit.
1. Go to HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\SearchScopes
2. Add a new key with a friendly name for the search engine (eg: Dictionary.com)
3. Under this new key, you need to add three values - two strings, and a DWORD:
-- String: "DisplayName" Value: "Dictionary.com" (this is the name that appears)
-- DWORD: "SortIndex" Value: 5 (increment this each time you add a new one)
-- String: "URL" Value: "http://dictionary.reference.com/search?q=%s" (%s gets replaced with the query)
Done.