This has been discussed many times and researched intensively and for now the answer is that there is no economical way to record HD from a digital cable box.
The technical reasons for this is that the HD signal is carried as an encrypted QAM signal. OTA HD is broadcast as 8-VSB, which can be tuned by the MYHD card and others. There may be some that can tune QAM but they cannot descramble.
Us digital cable folks are SOL until there's an HD box with either firewire or DVI out at which point a digital input card should allow HD recording.
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