browserName = navigator.appName;
browserVer = parseInt(navigator.appVersion);

if(browserName=="Netscape" && browserVer >= 3) ver = "yes";
else if (browserName == "Microsoft Internet Explorer" && browserVer >= 4) ver = "yes";
else ver = "no";
        
function active(imgName)
{
        if (ver == "yes")  {
        img1 = "images/" + imgName + "_2.gif";
        document [imgName].src = img1;
	}
}

function inactive(imgName){
        if (ver == "yes")  {
        img2 = "images/" + imgName + "_1.gif";
        document [imgName].src = img2;
        }
}