var nav = $('.thumb');

$(document).ready(function(){
	setBkgPos();
	$('.thumb').bind( 'mouseover', mMouseOver );
	$('.thumb').bind( 'mouseout', mMouseOut );

}); 

function setBkgPos()
{
	$('.thumb').css({backgroundPosition: '-15px 0px'});
}

function mMouseOver(e)
{

	$(this).stop().animate({ backgroundPosition:'(-70px 0px)'},800);
}

function mMouseOut(e)
{			
	$(this).stop().animate({backgroundPosition:'(0px 0px )'}, "slow", 
			// this section will be executed after the step.1 is done
			function(){
				$(this).animate( {backgroundPosition:'(-15px 0px)'}, "normal")
			});

}