Out of interest, are you talking about find gradations of quality here, or fundamental problems with playback on the N800?

My experience is that the latest mplayer is fine on the N800 - with the IMO minor caveats that

- it sometimes hangs / gets confused if you pause playback for a long while (more than a minute)

- it sometimes gets stuck at the start of the playback - can be fixed by pressing the select button a few times.

With the N800's native Media Player, I find that it gets stuck for no apparent reason after 15 minutes or so.

- Neil