Rotor banner, Toggle the display of an image banner and rotor banner view based on view results
You can display the image field of the node if the rotator banner is empty by outputting that field into the Empty Text field of the view that you are displaying. So you would only need the view's block in the region that you have both blocks currently. Make sure you have PHP input enabled in your empty text.

If the banner content is exclusive to that node's page, you can add a Node Reference CCK to the banner content type and tie the nid argument in views the the node reference field by adding that node reference field as a relationship in your view.