Hi!
I won't be able to confirm this, but I can give another solution for nVidia users.
From Geforce 8x00 all nVidia cards support CUDA technology.
I guess, today noone need GPU acceleration for XviD and below, so H.264 and VC-1 will be enough.
To get use of CUDA (at least for H.264 or VC1), you have to install CoreAVC and the latest nVidia driver for your card.
Then check the "Prefer CUDA acceleration" in CoreAVC options, make CoreAVC preferred decoder by checking that, too, and ta-da:
you have hw acceleration for the though ones (x264/h264/VC1) and for gratis:
you dont have to worry about DXVA compatibility, CoreAVC deals with (almost) any kind of h.264 encode versions (profiles).