// preload nav images & rollover states
homeon = new Image();
homeon.src = "images/btn_home_rol.gif";
homeoff = new Image();
homeoff.src = "images/btn_home.gif";

classeson = new Image();
classeson.src = "images/btn_classes_rol.gif";
classesoff = new Image();
classesoff.src = "images/btn_classes.gif";

instructionon = new Image();
instructionon.src = "images/btn_instruction_rol.gif";
instructionoff = new Image();
instructionoff.src = "images/btn_instruction.gif";

programson = new Image();
programson.src = "images/btn_programs_rol.gif";
programsoff = new Image();
programsoff.src = "images/btn_programs.gif";

whyon = new Image();
whyon.src = "images/btn_why_rol.gif";
whyoff = new Image();
whyoff.src = "images/btn_why.gif";

contacton = new Image();
contacton.src = "images/btn_contact_rol.gif";
contactoff = new Image();
contactoff.src = "images/btn_contact.gif";

var currentImage="";

function imgOn(imgName) {
   if (document.images) {
      document[imgName].src = eval(imgName + "on.src");
   }
}

function imgOff(imgName) {
   if (document.images && currentImage!=imgName) {
      document[imgName].src = eval(imgName + "off.src");
   }
}

function setCurrentImage(imgName) {
   currentImage = imgName;
   imgOn(imgName);
}