function alternateColor(id)
{ 
    if(document.getElementsByTagName)
    {  
        var table = document.getElementById(id); 
        if(table != null)
        {  
            var rows = table.getElementsByTagName("tr");  
            rows[0].className = "header";
            for(i = 1; i < rows.length; i++)
            {           
                 //manipulate rows 
                 if(i % 2 == 0)
                 { 
                   rows[i].className = "even"; 
                 }
                 else
                 { 
                   rows[i].className = "odd"; 
                 }       
            } 
        }
    } 
}