CableCARD
Ars Technica has graciously provided a comprehensive overview of the CableCARD technology. I would comment on the technology but I’m still trying to learn enough of building a decent home theater PC. I do know that I want to use the Ahanix MCE 601 or a Shuttle XPC case and will probably use a beta build of Windows Vista Media Center but other than that haven’t done too much learning.
Related Links for Future Reading:
Medie Center Edition Approved Components
this is totally offtopic, but you have the same name as the very famous xx century philosopher, leonard nelson
) wellknown for his critique of epistemology – it is impossible because dealing with it we cannot avoid committing the error of petitio principii 
)
cheers!