spiffnme: heres an example of a product that has a FAQ on some of the questions you asked about recording HD stuff on a HTPC using a HDTV card.
http://www.digitalconnection.com/Support/cn_myhd_1.asp

kcarlile: Here are some STB with firewire out. Connect firewire out to the digital input of a digital converter of any camcorder that accepts digital input via firewire. Camcorder converts it to HD DV format (I think) and pass the HD DV content via firewire to firewire input on PC using Video Vegas or firewire input on Mac using Final Cut Pro HD.
http://www.ramelectronics.net/html/KD-FIRE1080P.htm
This is dated but what happened to this.
http://digital-lifestyles.info/display_page.asp?section=platforms&id=1181

Here are MAC products that can record HD satellite feeds and and record using the Sats Program interface. The recorded show can be manipulated after recorded using Final Cut Pro in MAC. One transfers in firewire and the other STB can transfer via USB for captured programs.
http://www.elgato.com/index.php?file=products_eyetvhybridna
http://www.twinhan.com/product_terrestrial_9.asp

The mini mac is a great alternate to a HTPC.

What people do if their STB has firewire out they record not on harddrive due to capacity but on D-VHS which can store 50 gigs or 4 hours of 1080i HD content on D-VHS tape.
http://www.dvhsmovie.com/


http://www.quadloft.com/hometheater- new HT