//detect browser:
browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);
if (browserName == "Netscape" && browserVer >= 3) browserVer = "1";
else if (browserName == "Microsoft Internet Explorer" && browserVer == 4) browserVer = "1";
else browserVer = "2";

//preload images:
if (browserVer == 1) {
a1 = new Image(107,36);
a1.src = "a1.jpg";
a2 = new Image(107,36);
a2.src = "a2.jpg";
}

//image swapping function:
function switchImage(imgDocID, imgObjName) {
if (browserVer == 1) {
document.images[imgDocID].src = "http://www.clear2there.com/images/"+imgObjName;
return true;
}}