if (document.images) {
hoursoff=new Image();
hoursoff.src= "images/topnav/hoursoff.gif";
hourson=new Image();
hourson.src= "images/topnav/hourson.gif";
joinoff=new Image();
joinoff.src= "images/topnav/joinoff.gif";
joinon=new Image();
joinon.src= "images/topnav/joinon.gif";
mapoff=new Image();
mapoff.src= "images/topnav/mapoff.gif";
mapon=new Image();
mapon.src= "images/topnav/mapon.gif";
submitoff=new Image();
submitoff.src= "images/submitoff.gif";
submiton=new Image();
submiton.src= "images/submiton.gif";
}

function imageOn (imagename){
  document[imagename].src=eval(imagename+"on.src");
 }
function imageOff (imagename){
  document[imagename].src=eval(imagename+"off.src");
 }