You don't need to change your video card to watch youtube videos.
Follow this guide
http://smf.rantradio.com/index.php?topic=2162.0Works wonders im watching HD video on an athlon 1800+
,was imposible before to watch even the lowest settings using flash player.
Give it a shot know i do the same on my high end notebook and is much better than flash you dont see the ads know.