How do you make things float down the screen?

Code:

<script>

 //Here you can add your own picture for snow. Just change the url
var snowsrc="http://i13.servimg.com/u/f13/11/52/70/02/snowba10.png"
//how many snowflakes there will be (currently 12)
var no =40;
//How fast will the snow disappear (0 is never)
var hidesnowtime = 0;
//The height the snow will reach before it disappears ("windowheight" or "pageheight")
var snowdistance = "pageheight";
///////////////////////////////End of Settings///////////////////////////////////
var ie4up = (document.all) ? 1 : 0;
var ns6up = (document.getElementById&&!document.all) ? 1 : 0;

function iecompattest()
{
  return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
}

var dx, xp, yp;
var am, stx, sty;
var i, doc_width = 800, doc_height = 600;
 
if (ns6up)
{
  doc_width = self.innerWidth;
  doc_height = self.innerHeight;
}
else
if (ie4up)
{
  doc_width = document.body.clientWidth;
  doc_height = document.body.clientHeight;
}

dx = new Array();
xp = new Array();
yp = new Array();
am = new Array();
stx = new Array();
sty = new Array();

for (i = 0; i < no; ++ i)
{
  dx[i] = 0;
  xp[i] = Math.random()*(doc_width-50);
  yp[i] = Math.random()*doc_height;
  am[i] = Math.random()*20;
  stx[i] = 0.02 + Math.random()/10;
  sty[i] = 0.7 + Math.random();
  if (ie4up||ns6up)
  {
      if (i == 0)
      {
        document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><a href=\"http://rftactical.darkbb.com/index.htm\"><img src='"+snowsrc+"' border=\"0\"><\/a><\/div>");
      }
      else
      {
        document.write("<div id=\"dot"+ i +"\" style=\"POSITION: absolute; Z-INDEX: "+ i +"; VISIBILITY: visible; TOP: 15px; LEFT: 15px;\"><img src='"+snowsrc+"' border=\"0\"><\/div>");
      }
  }
}

function snowIE_NS6()
{
  doc_width = ns6up?window.innerWidth-10 : iecompattest().clientWidth-10;
  doc_height=(window.innerHeight && snowdistance=="windowheight")? window.innerHeight : (ie4up && snowdistance=="windowheight")?  iecompattest().clientHeight : (ie4up && !window.opera && snowdistance=="pageheight")? iecompattest().scrollHeight : iecompattest().offsetHeight;
  for (i = 0; i < no; ++ i)
  {
      yp[i] += sty[i];
      if (yp[i] > doc_height-50)
      {
        xp[i] = Math.random()*(doc_width-am[i]-30);
        yp[i] = 0;
        stx[i] = 0.02 + Math.random()/10;
        sty[i] = 0.7 + Math.random();
      }
      dx[i] += stx[i];
      document.getElementById("dot"+i).style.top=yp[i]+"px";
      document.getElementById("dot"+i).style.left=xp[i] + am[i]*Math.sin(dx[i])+"px";
  }
  snowtimer=setTimeout("snowIE_NS6()", 10);
}

function hidesnow()
{
  if (window.snowtimer) clearTimeout(snowtimer)
      for (i=0; i<no; i++) document.getElementById("dot"+i).style.visibility="hidden"
}
   

if (ie4up||ns6up)
{
  snowIE_NS6();
  if (hidesnowtime>0)
      setTimeout("hidesnow()", hidesnowtime*1000)
}
</script>

<SCRIPT type="text/javascript">
/*
Snow Fall 1 - no images - Java Script
Visit http://rainbow.arch.scriptmania.com/scripts/
for this script and many more
*/

// Set the number of snowflakes (more than 30 - 40 not recommended)
var snowmax=35

// Set the colors for the snow. Add as many colors as you like
var snowcolor=new Array("#AAAACC","#DDDDFF","#CCCCDD","#F3F3F3","#F0FFFF")

// Set the fonts, that create the snowflakes. Add as many fonts as you like
var snowtype=new Array("Arial Black","Arial Narrow","Times","Comic Sans MS")

// Set the letter that creates your snowflake (recommended: * )
var snowletter="*"

// Set the speed of sinking (recommended values range from 0.3 to 2)
var sinkspeed=0.6

// Set the maximum-size of your snowflakes
var snowmaxsize=22

// Set the minimal-size of your snowflakes
var snowminsize=8

// Set the snowing-zone
// Set 1 for all-over-snowing, set 2 for left-side-snowing
// Set 3 for center-snowing, set 4 for right-side-snowing
var snowingzone=1

/*
// * NO CONFIGURATION BELOW HERE *
*/

// Do not edit below this line
var snow=new Array()
var marginbottom
var marginright
var timer
var i_snow=0
var x_mv=new Array();
var crds=new Array();
var lftrght=new Array();
var browserinfos=navigator.userAgent
var ie5=document.all&&document.getElementById&&!browserinfos.match(/Opera/)
var ns6=document.getElementById&&!document.all
var opera=browserinfos.match(/Opera/)
var browserok=ie5||ns6||opera

function randommaker(range) {
rand=Math.floor(range*Math.random())
return rand
}

function initsnow() {
if (ie5 || opera) {
marginbottom = document.body.clientHeight
marginright = document.body.clientWidth
}
else if (ns6) {
marginbottom = window.innerHeight
marginright = window.innerWidth
}
var snowsizerange=snowmaxsize-snowminsize
for (i=0;i<=snowmax;i++) {
crds[i] = 0;
lftrght[i] = Math.random()*15;
x_mv[i] = 0.03 + Math.random()/10;
snow[i]=document.getElementById("s"+i)
snow[i].style.fontFamily=snowtype[randommaker(snowtype.length)]
snow[i].size=randommaker(snowsizerange)+snowminsize
snow[i].style.fontSize=snow[i].size
snow[i].style.color=snowcolor[randommaker(snowcolor.length)]
snow[i].sink=sinkspeed*snow[i].size/5
if (snowingzone==1) {snow[i].posx=randommaker(marginright-snow[i].size)}
if (snowingzone==2) {snow[i].posx=randommaker(marginright/2-snow[i].size)}
if (snowingzone==3) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/4}
if (snowingzone==4) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/2}
snow[i].posy=randommaker(2*marginbottom-marginbottom-2*snow[i].size)
snow[i].style.left=snow[i].posx
snow[i].style.top=snow[i].posy
}
movesnow()
}

function movesnow() {
for (i=0;i<=snowmax;i++) {
crds[i] += x_mv[i];
snow[i].posy+=snow[i].sink
snow[i].style.left=snow[i].posx+lftrght[i]*Math.sin(crds[i]);
snow[i].style.top=snow[i].posy

if (snow[i].posy>=marginbottom-2*snow[i].size || parseInt(snow[i].style.left)>(marginright-3*lftrght[i])){
if (snowingzone==1) {snow[i].posx=randommaker(marginright-snow[i].size)}
if (snowingzone==2) {snow[i].posx=randommaker(marginright/2-snow[i].size)}
if (snowingzone==3) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/4}
if (snowingzone==4) {snow[i].posx=randommaker(marginright/2-snow[i].size)+marginright/2}
snow[i].posy=0
}
}
var timer=setTimeout("movesnow()",50)
}

for (i=0;i<=snowmax;i++) {
document.write("<span id='s"+i+"' style='position:absolute;top:-"+snowmaxsize+"'>"+snowletter+"</span>")
}
if (browserok) {
window.onload=initsnow
}
</SCRIPT>
<p><font face="arial" size="-2">Free JavaScript from </font><br><font face="arial, helvetica" size="-2"><a href="http://rainbow.arch.scriptmania.com/scripts/">Rainbow Arch</a></font></p>