var objImage1 = new Image();
var objImage2 = new Image();
var objImage3 = new Image();
var objImage4 = new Image();
var objImage5 = new Image();
var objImage6 = new Image();

objImage1.src = "../images/nav_1b.gif";
objImage2.src = "../images/nav_2b.gif";
objImage3.src = "../images/nav_3b.gif";
objImage4.src = "../images/nav_4b.gif";
objImage5.src = "../images/nav_5b.gif";
objImage6.src = "../images/nav_6b.gif";

function setImage(imgOrig, imgNew) {
 
var ns = false;
var ie = false;
var version = parseInt(navigator.appVersion);
 
if (navigator.appName == "Netscape" && version <= 4)
ns = true;
else if (version <= 4) 
ie = true;
 
if (ns)
document.images[imgOrig].src = imgNew;
else
document.all[imgOrig].src = imgNew;
 
}