function openPopup(url){
	var properties = '';
	var win_width  = 700;
	var win_height = 430;
	
	winDim = getWindowsSize();
	
	offset_x = (winDim['width'] - win_width)/2;
	offset_y = (winDim['height'] - win_height)/2;
	
	properties = 'width='+ win_width + ',height=' + win_height + ',left=' + offset_x + ',top=' + offset_y;	
    window.open(url, '', properties);
    return false;
}

function getWindowsSize() {
  var myWidth = 0, myHeight = 0;
  var winDim = Array();
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  winDim['width']  = myWidth;
  winDim['height'] = myHeight;
  
  return winDim;
  
}