var xPos = 20;                                                             
var yPos = 60;                                                             
var step = 1;                                                             
var delay = 30;                                                              
var height = 0;                                                             
var Hoffset = 0;                                                             
var Woffset = 0;                                                             
var yon = 1;                                                             
var xon = 0;                                                             
var pause = true;                                                             
var interval;    
//document.all["img0"].style.top = yPos; 
//document.all["img1"].style.top = yPos;                                                          
function changePos() {                                                             
width = document.body.clientWidth;                                                             
height = document.body.clientHeight;                                                             
Hoffset = img0.offsetHeight;                                                             
Woffset = img0.offsetWidth;                 
document.all["img0"].style.left = document.body.scrollLeft+20;                                                          
document.all["img0"].style.top = yPos + document.body.scrollTop;  
document.all["img1"].style.left = document.body.scrollLeft+width-100;                                                          
document.all["img1"].style.top = yPos + document.body.scrollTop;                                                            
if (yon) {                                                             
yPos = yPos + step;                                                             
}                                                             
else {                                                             
yPos = yPos - step;                                                             
}                                                             
if (yPos < 0) {                                                             
yon = 1;                                                             
yPos = 0;                                                             
}                                                             
if (yPos >= (height - Hoffset)) {                                                             
yon = 0;                                                             
yPos = (height - Hoffset);                                                             
}                                                             
if (xon) {                                                             
xPos = xPos + step;                                                             
}                                                             
else {                                                             
xPos = xPos - step;                                                             
}                                                             
if (xPos < 0) {                                                             
xon = 1;                                                             
xPos = 0;                                                             
}                                                             
if (xPos >= (width - Woffset)) {                                                             
xon = 0;                                                             
xPos = (width - Woffset);                                                             
   }                                                             
}                                                             
function start() { 
if(screen.width<=800)
{                                                            
document.all["img0"].style.display = "none";   
document.all["img1"].style.display = "none";                                                          
}
interval = setInterval('changePos()', delay);                                                             
}