var prevBkgColor;
activateMenu = function(nav)
{
    /* currentStyle restricts the Javascript to IE only */
	if (document.all && document.getElementById(nav).currentStyle)
	{  
        var navroot = document.getElementById(nav);
        
        /* Get all the list items within the menu */
        var lis=navroot.getElementsByTagName("LI");  
        for (i=0; i<lis.length; i++)
		{        
           /* If the LI has another menu level */
            if(lis[i].lastChild.tagName=="UL")
			{           
                /* assign the function to the LI */
             	lis[i].onmouseover=function()
				{	
                   /* display the inner menu */
                   this.lastChild.style.display="block";
				   prevBkgColor = this.style.backgroundColor;
				   this.style.backgroundColor ="#CCCCCC";
       			}
                lis[i].onmouseout=function()
				{                       
                   this.lastChild.style.display="none";
				   this.style.backgroundColor = prevBkgColor;
                }
           }
        }
    }
}

<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
var months=new Array(13);
months[1]="Enero";
months[2]="Febrero";
months[3]="Marzo";
months[4]="Abril";
months[5]="Mayo";
months[6]="Junio";
months[7]="Julio";
months[8]="Agosto";
months[9]="Septiembre";
months[10]="Octubre";
months[11]="Noviembre";
months[12]="Diciembre";
var time=new Date();
var lmonth=months[time.getMonth() + 1];
var date=time.getDate();
var year=time.getYear();
if (year < 2000)    // Y2K Fix, Isaac Powell
year = year + 1900; // http://onyx.idbsu.edu/~ipowell

function fnGetDate()
{
	if (document.getElementById("fecha"))
	{
		var fecha = document.getElementById("fecha");
		fecha.innerHTML = '<div align="right">'+ date + ' de ' +  lmonth + ', ' + year +'</div>';
	}
}

window.onload= function(){
    /* pass the function the id of the top level UL */
    /* remove one, when only using one menu */
   // activateMenu('nav'); 
    activateMenu('vertnav'); 
	fnGetDate();
}