function launchPopup(url, top, width, height, scrollbars)
{     
    var aw = screen.availWidth - 10;
    var xc = (aw - width) / 2;

    var ah = screen.availHeight - 10;
    var yc = (ah - height) / 2;

    if(top == "middle")
	var popup = window.open(url, "mywindow", "scrollbars=" + scrollbars + ", top=" + yc + ", left=" + xc + ", width=" + width + ", height=" + height);   	    	
    else
    	var popup = window.open(url, "mywindow", "scrollbars=" + scrollbars + ", top=" + top + ", left=" + xc + ", width=" + width + ", height=" + height);   	

}