var currentId = 'header1';
var topIndex = 3;

function fadeHeader(nextId)
{
	if(nextId != currentId)
	{
		var next = document.getElementById(nextId);
		
		topIndex++;
		new Element.setOpacity(next, 0);
		next.style.visible = 'hidden';
		next.style.zIndex = topIndex;
		new Effect.Fade(next, { 
			from: 0.0,
			to: 1.0,
			afterFinish: function() 
			{
				currentId = nextId;
			} } );
	}
}