function RandomNumber() 
{
 var today = new Date(); var num= Math.abs(Math.sin(today.getTime()/1000)); return num;
}
function RandomGraphics() 
{
  var x = RandomNumber();
  if (x > .75) {document.write("<img width=200 height=300 src='/i/b0001.gif' border=0>"); return;}
  if (x > .50) {document.write("<img width=200 height=400 src='/i/b0002.gif' border=0>"); return;}
  if (x > .25) {document.write("<img width=200 height=300 src='/i/b0003.gif' border=0>"); return;}
  if (x > 0)   {document.write("<img width=200 height=400 src='/i/b0004.gif' border=0>"); return;}
}
RandomGraphics();