var popup = null;

function launchPopup(URL, windowName, windowWidth, windowHeight, scrollbars)
{
	var xposition = 400; 
	var yposition = 300;
	
    if ((parseInt(navigator.appVersion) >= 4 )) {
        xposition = (screen.width - windowWidth) / 2;
        yposition = (screen.height - windowHeight) / 2;
    }
	
	if (!scrollbars) var scrollbars = 0;
	
    var args = "width=" + windowWidth + ","
	    	+ "height=" + windowHeight + ","
		    + "toolbar=0,"
	    	+ "location=0,"
		    + "menubar=0,"
		    + "scrollbars=1,"
		    + "status=0,"
		    + "titlebar=0,"
		    + "hotkeys=0,"
		    + "screenx=" + xposition + ","  // NN Only
		    + "screeny=" + yposition + ","  // NN Only
		    + "left=" + xposition + ","     // IE Only
		    + "top=" + yposition;           // IE Only
		
	if (popup != null && !popup.closed) {
		popup.close();
	}
	popup = window.open(URL, windowName, args);
	
	popup.focus();
}