Can anyone recommend a good HD TV Tuner for my PC

All digital tuners (terrestrial, satelite and cable) and inherently HD capable as they do not process the video or audio themselfs, they just send the streams to the drivers and playback software to deal with.

Satellite HD is usually broadcst in DVB-S2, these cards aren't that common (although they are gettimg more wide spread all the time) and i have no idea what is good and what isn't.

There is no easy way to get HD in the UK anyway. Sky use a closed system that doesn't easily allow using a PC based DVB-S/S2 card. Freeview has no HD unless you are within the Crystal Palace transmitter (London). There might be test transmitions from the BBC on one of the Free To Air satellites, but i'm not 100%.

Any more details on what you want to do with the card?