I use TheaterTek for SD DVD playback and TMT3 for HD playback. This combo works well for me in VMC with MyMovies. I don't install extra codecs that could cause problems and just save to folder. TT looks fine for me and is written to take advantage of Nvidia graphics cards.
With MyMovies, click DVD cover and TT starts, click Blu-ray or HD DVD cover and TMT3 starts. Couldn't be easier.
With MyMovies, click DVD cover and TT starts, click Blu-ray or HD DVD cover and TMT3 starts. Couldn't be easier.