multimedia in Linux

The recent letters on TIvo and Myth TV in the Dec issue were interesting. I recently bought a Dish Network VIP622 to do some engineering tests with the remote control receiver. I put the drive in an external HDD enclosure and discovered that the system works under Linux. It also has an off air TV tuner for both analog and HD TV signals. I assume you can also record off air programs with it, so they have apparently made a system which does what I would like to do with a Linux computer. Unfortunately, Echostar (Dish Network) does not allow the user to use it unless you are subscribed to their satellite service.
Has anyone looked at one of these units? Can I make up a computer to do the same thing? Can I modify the files on the HDD so I can use it as a TV receiver with recording capability?

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