var base = (Prototype.Browser.IE ? 0 : 0);
        var factor = (Prototype.Browser.IE ? 1 : 1);
        var index = 0;
                
        function Previous()
        {
            index--;
            Effect.SlideLeft(display.childNodes[base + index*factor]);
            ShowHideNavigation();
        }
        
        function Next()
        {
            Effect.SlideRight(display.childNodes[base + index++*factor]); //Up
            ShowHideNavigation();
                        
        }
        
        function ShowHideNavigation()
        {
            if (index == 0) 
                $('leftNav').makeClipping().hide();
            else
                $('leftNav').makeClipping().show();                

            if ((base + index*factor) >= (total - base))
                $('rightNav').makeClipping().hide();
            else
                $('rightNav').makeClipping().show();                
            return;
        }