function showPlayers (id)
{
	var xhttp;

	if (window.XMLHttpRequest)
		xhttp = new XMLHttpRequest();
	else
		xhttp = new ActiveXObject("MSXML2.XMLHTTP.3.0");


	xhttp.open ("GET", "?ajax=1&server_id=" + id, true);

	xhttp.onreadystatechange = function()
	{
		if (xhttp.readyState == 4)
		{
			if (xhttp.status == 200)
			{
				if (xhttp.responseText)
				{
					document.getElementById('players').innerHTML = xhttp.responseText;
					updateSize ();
					fireMyPopup ();
					//document.getElementById(
				}
			}
		}
	}

	xhttp.send ("");
}

function updateSize()
{
// Determine how much the visitor had scrolled

var scrolledX, scrolledY;
if( self.pageYOffset ) {
  scrolledX = self.pageXOffset;
  scrolledY = self.pageYOffset;
} else if( document.documentElement && document.documentElement.scrollTop ) {
  scrolledX = document.documentElement.scrollLeft;
  scrolledY = document.documentElement.scrollTop;
} else if( document.body ) {
  scrolledX = document.body.scrollLeft;
  scrolledY = document.body.scrollTop;
}

// Determine the coordinates of the center of browser's window

var centerX, centerY;
if( self.innerHeight ) {
  centerX = self.innerWidth;
  centerY = self.innerHeight;
} else if( document.documentElement && document.documentElement.clientHeight ) {
  centerX = document.documentElement.clientWidth;
  centerY = document.documentElement.clientHeight;
} else if( document.body ) {
  centerX = document.body.clientWidth;
  centerY = document.body.clientHeight;
}

  var me = document.getElementById("mypopup");

  var leftOffset = scrolledX + (centerX - me.clientWidth) / 2;
  var topOffset = scrolledY + (centerY - me.clientHeight) / 2;

  document.getElementById("mypopup").style.top = topOffset + "px";
  document.getElementById("mypopup").style.left = leftOffset + "px";

}

function fireMyPopup()
{
<!-- Due to different browser naming of certain key global variables, we need to do three different tests to determine their values -->

  document.getElementById("mypopup").style.visibility = "visible";
}