Dvd decoder choices

For XP, running media player 9, I’ve heard that some video cards have onboard decoders. Is this for playing dvd’s? I have a 8800 GT (which I thought was a decent card) and know that the decoders won’t play all movies from experience.

Will the hardware option pretty much cover all the dvd’s out there? If this can be done, I’m guessing this is better than taking the software route.

Anyone recommend a card that can do this at reasonble price?

And what about the plug-in – tried Nvidia long time back, but are there better solutions (including for HD). I don’t think the Nvidia does HD.

Now that I have a new flatscreen which gives a geat display (AOC) I might as well take advantage with some flicks.