if (document.images) {

  image1on = new Image();
  image1on.src = "images/nav/listings_on.gif";
  
  image2on = new Image();
  image2on.src = "images/nav/about_on.gif";

  image3on = new Image();
  image3on.src = "images/nav/links_on.gif";

  image4on = new Image();
  image4on.src = "images/nav/photos_on.gif";

  image5on = new Image();
  image5on.src = "images/nav/pilot_on.gif";

  image6on = new Image();
  image6on.src = "images/nav/news_on.gif";

  image7on = new Image();
  image7on.src = "images/nav/slideshows_on.gif";

  image1off = new Image();
  image1off.src = "images/nav/listings_off.gif";
  
  image2off = new Image();
  image2off.src = "images/nav/about_off.gif";
  
  image3off = new Image();
  image3off.src = "images/nav/links_off.gif";
  
  image4off = new Image();
  image4off.src = "images/nav/photos_off.gif";
  
  image5off = new Image();
  image5off.src = "images/nav/pilot_off.gif";
  
  image6off = new Image();
  image6off.src = "images/nav/news_off.gif";
  
  image7off = new Image();
  image7off.src = "images/nav/slideshows_off.gif";
  
}
function turnOn(imageName) {
  if (document.images) {
    document[imageName].src = eval(imageName + "on.src");
  }
}

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

<!-- 
//browser detection
bName = navigator.appName; 
bVer = parseInt(navigator.appVersion);	
	if ((bName == "Netscape" && bVer >= 3) || 		
	    (bName == "Microsoft Internet Explorer" && bVer >= 4)) br = "n3";
    else br = "n2"
	
if (br== "n3") {

//introduce rollover images for buttons: prev, next, emailus, vt, more info and more details
var preva = new Image();
preva.src = "images/prev-a.gif";
var prevb = new Image();
prevb.src = "images/prev-b.gif";

var nexta = new Image();
nexta.src = "images/next-a.gif";
var nextb = new Image();
nextb.src = "images/next-b.gif";

var vta = new Image();
vta.src = "images/vt-a.gif";
var vtb = new Image();
vtb.src = "images/vt-b.gif";

var emaila = new Image();
emaila.src = "images/emailus-a.gif";
var emailb = new Image();
emailb.src = "images/emailus-b.gif";

var moreinfoa = new Image();
moreinfoa.src = "images/moreinfo-a.gif";
var moreinfob = new Image();
moreinfob.src = "images/moreinfo-b.gif";

var moredetailsa = new Image();
moredetailsa.src = "images/moredetails-a.gif";
var moredetailsb = new Image();
moredetailsb.src = "images/moredetails-b.gif";



//introduce rollover images for buttons: Browse Listings, Learn About Us, Community Links
var listingsa = new Image();
listingsa.src = "images1/listings-a.gif";
var listingsb = new Image();
listingsb.src = "images1/listings-b.gif";

var usa = new Image();
usa.src = "images1/us-a.gif";
var usb = new Image();
usb.src = "images1/us-b.gif";

var linksa = new Image();
linksa.src = "images1/links-a.gif";
var linksb = new Image();
linksb.src = "images1/links-b.gif";
}

// -->
//open window for property photos
function openWin(URL) {
aWindow = window.open(URL,"Window","scrollbars=yes,resizable=1,width=700,height=500");
}
// -->