i would upgrade everything

sky plus or HD will give you dolby digital quality for all your movie and sports channels.
your amplifier is a bit old, best to upgrade to a newer one which can also handle the HDMI switching, meaning less cables to run to your TV, and can also decode the latest audio tracks on HD/bluray movies, giving up to 7.1 quality sound.
DVD player.I would hold off on getting a high def dvd for the moment until the "war" is over, and instead by a nice machine which can upscale to 1080p. Can pick one up for under 100 quid.