browser_name = navigator.appName;
browser_version = parseFloat(navigator.appVersion);

if (browser_name == "Netscape" && browser_version >= 3.0) { roll = 'true'; }
else if (browser_name == "Microsoft Internet Explorer" && browser_version >= 3.0) { roll = 'true'; }
else { roll = 'false'; }

function over(img,ref) { if (roll == 'true') { document.images[img].src = ref; } }
function out(img,ref) { if (roll == 'true') { document.images[img].src = ref; } }

if (roll == 'true')
{
a1=new Image;a1.src="images/button1.gif";
a2=new Image;a2.src="images/button1-.gif";
a3=new Image;a3.src="images/button2.gif";
a4=new Image;a4.src="images/button2-.gif";
a5=new Image;a5.src="images/button3.gif";
a6=new Image;a6.src="images/button3-.gif";
a7=new Image;a7.src="images/button4.gif";
a8=new Image;a8.src="images/button4-.gif";
a9=new Image;a9.src="images/button5.gif";
a10=new Image;a10.src="images/button5-.gif";
a11=new Image;a11.src="images/button6.gif";
a12=new Image;a12.src="images/button6-.gif";
a13=new Image;a13.src="images/button7.gif";
a14=new Image;a14.src="images/button7-.gif";
}