function Pop(file,popW,popH,xtras) {
// Open Pop Up Window
	var w = 0, h = 0;
	// Get Available Screen Width ( w ) and Height ( h ) 
	if (document.all || document.layers) {
	   w = screen.availWidth;
	   h = screen.availHeight;
	}
	// Get Center Values
	var leftPos = ((w-popW)/2)-16, topPos = ((h-popH)/2)-16;
	
	// Open the window
	newWindow = window.open(file,'Pop', xtras + ',width=' + popW + ',height=' + popH + ',top=' + topPos + ',left=' + leftPos);
	newWindow.focus()	
}