Maybe you live in an apartment and can't get a good signal or put out a big honking antenna. Maybe you don't want the antenna on your house, or don't have a decoder box already and don't want to put out the $400 or so dollars and would rather pay $10/month for the DCT5100. Perhaps you have digital cable and have been using your HDTV for DVDs and this is a simple upgrade path without adding an antenna/dish combo. Take your pick. This product may not be for everyone, but I'm sure some people will get use from it.
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Dave
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Dave