var NewWin = null;
function PopUp(theURL,winName,features,x,y)
{
 var w = screen.width; // Get the width of the screen
 var h = screen.height; // Get the height of the screen
 // Where to place the Window
 var left = (w/2) - (parseInt(x)/2);
 var top  = (h/2) - (parseInt(y)/2);
 closePopUp();
 NewWin = window.open(theURL,winName,features+',left='+left+',top='+top);
}
function closePopUp()
{  
  if (NewWin && NewWin.open && !NewWin.closed) NewWin.close();
}
function MM_openBrWindow(theURL,winName,features,x,y)
{
 PopUp(theURL,winName,features,375,500); 
}