mattman255 said:"The GeForce 6800 models featured the 1st generation of our programmable
video technology which includes support for high-definition MPEG2 video
decode and standard definition MPEG2 encode, as well as advanced post
processing features such as motion adaptive deinterlacing, and inverse 3:2
pulldown.
The GeForce 6600 models have the same 1st generation programmable video
technology support as the GeForce 6800 models. However, the GeForce 6600
models also include hardware acceleration for high-definition Windows Media
Video (WMV) decode.
6800 won't do HD WMV. The card is incapable of doing it, and they're admitting here. The second paragraph explicitly says that only the 6600's can do it.