bName = navigator.appName;
bVersn = parseInt(navigator.appVersion);
versn = "vNOT";

if (bName == "Netscape" && bVersn >= 3) versn = "vOK";
if (bName == "Microsoft Internet Explorer" && bVersn >= 4) versn = "vOK";
if (bName == "Opera" && bVersn >= 5) versn = "vOK";

if (versn != "vNOT") {
arr1a=new Image(); arr1a.src="img0/up1.gif";
arr1b=new Image(); arr1b.src="img0/up2.gif";
} else {
arr1a=""; arr1b=""; }

function chM(imgsrc1, imgsrc2) {
    if (versn == "vNOT") return false;
	document.images[imgsrc1].src=imgsrc2.src;
	return true;}