Just found occasionally that Chronos has a new 2.5" MP2200 which is capable to play mkv files. It seems to be suitable for 2.5" internal HDD.
Strange is that Google seems totally not to be aware of this unit.
Hi have you looked at the tivx range of HDD media players. Thay can be a little price but thay are extreamly good at what thay do iv had the m-4100sh for about a year. It will run just about anything i can chuck at it have a look there is quite a range.
plus the fact that it runs with the maximum resolution of 1920-1080p with HDMI 1.3 makes it a good peace of kit to use. Put it this way iv never had any problems with mine and im running H.264 files of about 11GB at times with no loss in picture quality or audio but have a look and see what you think!