var cando = false;
var browserName = navigator.appName;
var browserVer = parseInt(navigator.appVersion);

if (browserName == "Netscape" && browserVer >= 3)
	cando = true;
else
	if( browserVer >=4 ) cando=true;
	

function swtch(num,imgname){
        if( cando )
        eval("document.getElementById('"+imgname+"').src = im[num].src;");
}