The results of my experimenting for the last month with NZ DVBT transmissions with respect to video cards are:
The 7600GS has NO hardware decoding for H.264.
The NVidia website leads you astray with this fact. The card supports Purevideo BUT NOT Purevideo HD.
My CPU usage was 30-50% with a E6750 (2.6GHz Core2duo), recent motherboard and fast memory.
Yes my system with the 7600GS and DVB Viewer would decode the broadcast with software decoding, but the result was quite jittery and annoying to watch..
After changing to an 8500GT today the difference is remarkable!
The jittery video is gone and my CPU is down to 5-8% while watching TV3 which is apparently the worst channel at present due to the de-interlacing requirements.
I second the idea to set up a list of video cards that have been 'actually' tested by members and not assumed to work because of (sometimes) misleading information on the net.
My research was solely on NVidia cards that would support H.264 hardware decoding and my end conclusion was that only the 8xxx and 9xxx cards are fully capable.
The exception (I thought) was the 8400 which didn't have the right graphics engine, but I see it seems to work for another member..