There are several cards available for HDTV. Both analog and digital TV cards are listed at:
Most of the cards are analog TV. Those with HDTV somewhere in the name will work for HDTV. Note there are versions for the US/Korea which share the same standard and others for Australia. The Aussie version also has "DVB-T" in the name.
I own DViCO FusionHDTV 3 Gold-Q and FusionHDTV 5 Gold. The newer version 5 has an improved tuner and HDTV demodulator.
Both work with mythTV in Austin TX. I haven't figured out how to configure mythTV to use both the analog and digital capabilities of a FusionHDTV card together. The cards share the same tuner for digital and analog. This confuses mythTV because it assumes analog and digital TV are completely independent and do not share tuners. Either one works by itself - just don't configure mythTV to have both digital and analog capabilities on the same card.