function setCont()
{
  _setCont();
  window.setInterval("_setCont()", 50);
}

function _setCont()
{
  var thisContent = document.getElementById("content");
  var thisHeader = document.getElementById("header");
  var thisFooter = document.getElementById("footer");
  var winHeight = 0;
  if(window.innerHeight)
  {
    winHeight = window.innerHeight;
  }
  else if(document.documentElement.clientHeight)
  {
    winHeight = document.documentElement.clientHeight;
  }
  else if (document.body.clientHeight)
  {
    winHeight = document.body.clientHeight;
  }

  var contHeight = winHeight - thisHeader.offsetHeight - thisFooter.offsetHeight - 10;
  
  if(contHeight > 250)
  { 
    thisContent.style.height = contHeight + "Px";
    thisFooter.style.position = "absolute";
  }
  else
  {
    thisContent.style.height = "auto";
    thisFooter.style.position = "relative";
  }
}