if (document.images) {
    // preload the alternate images offscreen
   homeon = new Image();
   homeon.src = "../images/42-on.gif";
   tfalon = new Image();
   tfalon.src = "../images/43-on.gif";
   balanceon = new Image();
   balanceon.src = "../images/44-on.gif";
   resourceon = new Image();
   resourceon.src = "../images/45-on.gif";
   seminaron = new Image();
   seminaron.src = "../images/46-on.gif";
   practiceon = new Image();
   practiceon.src = "../images/48-on.gif";
   contacton = new Image();
   contacton.src = "../images/49-on.gif";
   homeoff = new Image();
   homeoff.src = "../images/42-off.gif";
   tfaloff = new Image();
   tfaloff.src = "../images/43-off.gif";
   balanceoff = new Image();
   balanceoff.src = "../images/44-off.gif";
   resourceoff = new Image();
   resourceoff.src = "../images/45-off.gif";
   seminaroff = new Image();
   seminaroff.src = "../images/46-off.gif";
   practiceoff = new Image();
   practiceoff.src = "../images/48-off.gif";
   contactoff = new Image();
   contactoff.src = "../images/49-off.gif";
}

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

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