function alternateRows()
{	
el = document.getElementsByTagName('table');  
for (i=0; i<el.length; i++)  
if (el[i].className == 'dataTable')
{     
rows = el[i].getElementsByTagName('tr');  
for (j=0; j<rows.length; j++)     
rows[j].className = 'alternateRow' + (j % 2); 
}
}