I like the idea of stacked screens. How can you swap between which screen is up?

This is for WoW and Windows 7.

w1, w2, w3 ,w4.

w1 is full screen. How can I on the fly swap to lets say w4? Then when w4 is full screen swap to w 3?

Currently I use a swap key but that doesnt seem like it will work since I can't hover over the other screen.

Thanks.