Header Right Widget Customizations

Right now I have a header right widget that allows space for a 728×90 leaderboard. My ad service alternates 728×90 and 970×250 ads in the same space though and I would like to make it so that when the larger ad size displays, the header right widget area automatically pops down BELOW the header, displays the full width of the ad, and the header centers above it. Is there anyone who knows the code to do this?

I’m using the Cook’d Pro theme on the Genesis Framework.