I’ve written a small how to about ATI HD series graphics cards and the way they should be set up for hardware acceleration of matroska high-definition files.
You can read it here.
Hope this helps.
Tags: AGP, ATI, Audio, Catalyst, DVXA, HD2400, HD2600, HD2XXX, HD3450, HD3650, HD3850, HD3870, HD4350, HD4550, HD4650, HD4670, HDMI, Hotfix, How to, Matroska, Media Player Classic, Microsoft UAA, PCI-E, Realtek HDMI Audio