$(document).ready(
	function()
	{
		var link = $( '#header span.menu_image' );
		var hoverLink = $( '#header span.menu_image_hover' );
		if( link.length > 0 )
		{
			link.each( function(index) 
			{
				$( this ).parent().mouseenter( function(e) 
				{
					$( link[ index ] ).hide();
					$( hoverLink[ index ] ).show();
				} );
				$( this ).parent().mouseleave( function(e) 
				{
					$( hoverLink[ index ] ).hide();
					$( link[ index ] ).show();
				} );
			} );
		}
	}
);