Compare Side by Side Toolbar

Removed in 2007
In Excel 2003 this was displayed as a toolbar which was automatically displayed.

Synchronous Scrolling - Locks the two windows together wherever they currently are so that they scroll together.
Reset Window - Resets the position of the windows so they share the screen equally. The window that is currently active is the one that will appear on top.
Close Side by Side - Releases both the windows and returns them to their original orientation. This button was removed in 2007 because the View Side by Side is now a toggle button. In 2007 you can just press the View Side by Side button again to close this feature.