i played 1080p mkv of 22gb file size, but i think the limit is not the file size, but the bitrate. they said it can support up to 40 mb/s bitrate, i think 40 mb/s but only via cable, coz wifi will lag at 40 mb/s. new boxes are dual-core, they should support much more. also use the default integrated player, its tuned to use the resources of the box. no other media players in my test performed better. and the default media player is pretty good and many options. atv 1000 and 2000 have the same firmware, but i think 3000 and 4000 are different, but could be wrong. i think 3000/4000 are not that popular, as integrated hd is not such a big deal. its more convenient to have an external hd (to copy files onto it). no movie organiser, just browse the folder, select file, open with media player. would be nice to have an application, that based on the movie file name will connect to imdb and display info. if any know such application, let us know.