$(document).ready(function(){
    lastBlock = $("#a1");
    maxWidth = 180;
    minWidth = 120;	

    $("ul li a").hover(
      function(){
        $(lastBlock).animate({width: minWidth+"px"}, { queue:false, duration:400 });
		$(this).animate({width: maxWidth+"px"}, { queue:false, duration:400});
		lastBlock = this;
      }
    );
});