Yep, did all the updates to the OS as recommended, and then did this:
Haali Media Splitter: The de facto video file parser. Direct download link: Haali Media Splitter.
ffdshow: Download the latest and greatest build from here: ffdshow SVN builds, e.g. ffdshow_rev2405_20081201_clsid.exe. Run the installer to install and configure the video and audio decoders.
AC3Filter: For those that use SPDIF out on your systems, this is the best-performing audio decoder. Get it here: AC3Filter. Download and run the installer. Once it's installed, run it's configuration (in your Start Menu) and enable the "Use SPDIF" checkbox if you plan to pass-through all AC3 and DTS to your receiver.
MPC Video Decoder: The best, free DXVA-capable H.264/AVC/VC-1 decoder. Direct download link to version 1.2.908.0: MPC Video Decoder.
Download the zip file to a safe location.
Create the following folder under your Program Files: C:\\Program Files\\MPCVideoDecoder.
From the zip file you downloaded extract MPCVideoDec.ax to C:\\Program Files\\MPCVideoDecoder.
From the Start menu select Run and type in the following command: regsvr32 "C:\\Program Files\\MPCVideoDecoder\\MPCVideoDec.ax". You should get a pop-up message telling you the filter/file was registered successfully. That means the decoder is installed and registered on your system.
Now that the decoder is registered on your system it has to be configured for DXVA. Get RadLight Filter Manager here: RadLight Filter Manager. Run it, and under DirectShow Filters select "MPC - Video decoder" and hit the Property Page button. Now in MPC Video Decoder's properties, go to the Codecs tab and enable all of the check boxes, particularly "H.264/AVC (DXVA)" and "VC1 (DXVA)".
All ecept the AC3filter which I don't use (at least for now).
After installing all that is that I tried playing back some .mkv files and had Media Player crash on me...