The more of the aged material I read the more I am confused. I have an x64 W7 install and am happy to use the MS decoders for the low res avi files, they look fine. I am trying to get 1080 .mkv files to play. 720 plays OK even though graphstudio shows DTV-DVD in use. The machine is plenty powerful, never gets above 1 or 2% on xvid, about 3% on DVD (2120T, 8Gb ram). I have been using a Lenny T61 as a testbed which is not ideal as the graphics are pre DXVA and I will want to use DXVA if poss because I have a 1Gb DDR3 6570 GPU. Installed late 2011 build ffdshow x64 and haali 126.96.36.199, tried the gabest and had no fun on the laptop. Audio tray icon shows as does haali icon but no ffdshow video. I ran graphstudio and DTV-DVD is placed, no sign of haali though the systray icon shows. I have to tread careful because I have a tuner card installed. In short I will let 7MC handle MS own and divx/xvid, not to break HD live TV and be able to play 1080 .mkv. Tried disabling x64 DTV-DVD using 7DS tweaker to no avail. Any pointers or guidance would be appreciated. No I havent tried the shark codec packs, my 9 yr old s478 now worth 10 bob gallatin chip and 7600gs card does 1080p .mkv at 30% CPU and no hardware accel, albeit at 32 bit but no codec pack. MS have made the job difficult for the hard of thinking like myself. I should of course add that 1080 files are opened in MC and seen in the library but fart and stutter and intermittantly pixelatem not a very satisfying experience.