function Switch(item,on) {
var sTmp;
  if (item == "menu1")  {
  if (on)    {
  sTmp = "this.document." + item +".src = \"images/home_on.jpg\"";
  eval(sTmp); 
  } else {
  sTmp = "this.document." + item +".src = \"images/home.jpg\"";
  eval(sTmp);
  }
  } 
  if (item == "menu2")  {
  if (on)    {
  sTmp = "this.document." + item +".src = \"images/about_on.jpg\"";
  eval(sTmp); 
  } else {
  sTmp = "this.document." + item +".src = \"images/about.jpg\"";
  eval(sTmp);
  }
  }
  if (item == "menu3")  {
  if (on)    {
  sTmp = "this.document." + item +".src = \"images/contact_on.jpg\"";
  eval(sTmp); 
  } else {
  sTmp = "this.document." + item +".src = \"images/contact.jpg\"";
  eval(sTmp);
  }
  }
  
  
  }