Carol, see our portfolio for some of flash banner examples at
www.adultstyleguide.com > promo materials
the ad you're talking about is usually made with DHTML layers, or flash poping out new window with specific dimentions w/o any browser interface items and hidden borders.
if you're going after eye catching look of the ad, i suggest using flash and dhtml (it would be the best to disregard netscape although different versions can be build for different browsers, mainly depending on your targeting audience)
cheers