Code
<script>   
var no = 1;   
var speed = 299;   
var ns4up = (document.layers) ? 1 : 0;   
var ie4up = (document.all) ? 1 : 0;   
var s, x, y, sn, cs;   
var a, r, cx, cy;   
var i, doc_width = 800, doc_height = 600;   
if (ns4up) {   
doc_width = self.innerWidth;   
doc_height = self.innerHeight;   
}   
else   
if (ie4up) {   
doc_width = document.body.clientWidth;   
doc_height = document.body.clientHeight;   
}   
x = new Array();   
y = new Array();   
r = new Array();   
cx = new Array();   
cy = new Array();   
s = 8;   
for (i = 0; i < no; ++ i) {       
initRain();   
if (ns4up) {   
if (i == 0) {   
document.write("<layer name=\"dot"+ i +"\" left=\"1\" ");   
document.write("top=\"1\" visibility=\"show\"><img src=\"http://gamesmir.com/scripts/tarakan_by_crystall.gif\" width=75 height=56>");   
document.write("</layer>");   
}   
else {   
document.write("<layer name=\"dot"+ i +"\" left=\"1\" ");   
document.write("top=\"1\" visibility=\"show\"><img src=\"http://gamesmir.com/scripts/tarakan_by_crystall.gif\" width=75 height=56></layer>");   
       }   
}   
else       
if (ie4up) {   
if (i == 0) {   
document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");   
document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");   
document.write("visible; TOP: 15px; LEFT: 15px;\"><img src=\"http://gamesmir.com/scripts/tarakan_by_crystall.gif\" width=75 height=56></div>");   
}   
else {   
document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");   
document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");   
document.write("visible; TOP: 15px; LEFT: 15px;\"><img src=\"http://gamesmir.com/scripts/tarakan_by_crystall.gif\" width=75 height=56></div>");   
          }   
       }   
}   
function initRain() {   
a = 6;   
r[i] = 1;   
sn = Math.sin(a);   
cs = Math.cos(a);   
cx[i] = Math.random() * doc_width + 1;   
cy[i] = Math.random() * doc_height + 1;   
x[i] = r[i] * sn + cx[i];   
y[i] = cy[i];   
}   
function makeRain() {   
r[i] = 1;   
cx[i] = Math.random() * doc_width + 1;   
cy[i] = 1;   
x[i] = r[i] * sn + cx[i];   
y[i] = r[i] * cs + cy[i];   
}   
function updateRain() {   
r[i] += s;   
x[i] = r[i] * sn + cx[i];   
y[i] = r[i] * cs + cy[i];   
}   
function raindropNS() {   
for (i = 0; i < no; ++ i) {   
updateRain();   
if ((x[i] <= 1) || (x[i] >= (doc_width - 20)) || (y[i] >= (doc_height - 20))) {   
makeRain();   
doc_width = self.innerWidth;   
doc_height = self.innerHeight;   
}   
document.layers["dot"+i].top = y[i];   
document.layers["dot"+i].left = x[i];   
}   
setTimeout("raindropNS()", speed);   
}   
function raindropIE() {   
for (i = 0; i < no; ++ i) {   
updateRain();   
if ((x[i] <= 1) || (x[i] >= (doc_width - 20)) || (y[i] >= (doc_height - 20))) {   
makeRain();   
doc_width = document.body.clientWidth;   
doc_height = document.body.clientHeight;   
}   
document.all["dot"+i].style.pixelTop = y[i];   
document.all["dot"+i].style.pixelLeft = x[i];   
}   
setTimeout("raindropIE()", speed);   
}   
if (ns4up) {   
raindropNS();   
}   
else   
if (ie4up) {   
raindropIE();   
}   
</script>