Computer display on monitor & LCD HDTV simultaneously?

I got a VGA cable and it works fine but I want the computer to display on its monitor AND the HDTV at the same time. I bought this a href="http://www.monoprice.com/products/product.asp?c_id=101&cp_id=10104&cs_id=1010404&p_id=2679&seq=1&format=2&style=" rel="nofollow"http://www.monoprice.com/products/produc…/a but it does not do what I thought it would. I have a Radeon 9200SE graphics card if that helps anyone. Thanks.