HD, Transport Streams, huh, what?

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So if I have HD Cable w/STB HD out (DVI I think) All I would need is a DVI Capture card to get the video/audio streams onto the PVR... Because all the HD decoding is handled by the STB...?

It doesnt really work like that. There isnt really any (consumer) digital devices that record from the output of a set top box (the devices have no DVI or HDMI inputs, usually just a coax or antenna socket). The capture card tunes the original signal and the software does the remuxing etc.