I've been using the latest version of Nero Recode to convert my DVDs to H.264 and 5.1 AAC audio.  They play and look great on my pc.  I've been trying to use Nero Media Home 4 to transcode them for play on my Xbox360 (which doesn't support 5.1).  While they will play, the picture is extremely blocky and pixelated.  Other files using x.264 downloaded off the net do not have this problem, so it is a bit puzzling.  I can see where the transcoding might cause this, but since the Xbox supports the H.264 codec already, I don't know why the picture is suddenly being altered.  Any sugguestions?