A possible alternative would be to use a program such as LaunchBar or Google's Quick Search Box (made by the developer of Quicksilver).
Both options allow you to press a keyboard shortcut and quick launch applications, or perform a search.
For example; LaunchBar you would press your keyboard shortcut (eg. Command-Space) to bring LaunchBar to the front, then type an abbreviation for Google Search (eg. g or even ggl - it learns as you use it), press space and you can enter your search term. A Spotlight search would be done using a different abbreviation but the results of both searches would not be together.
Google Quick Search Box works similar but doesn't require you to explicitly state what kind of search you want to do (Spotlight or Google). It's also free compared to LaunchBar being shareware. You also need to enable Spotlight results in GQSB in order to view Spotlight results but like LaunchBar you can not view the Google Search results at the same time.