Jim is in the process of "cutting the cable," and he's looking to get a good HD antenna. Leo says that over-the-air signal is the best quality HD because it's uncompressed. Leo advises using AntennaWeb.org. It'll not only tell him what stations work best, it'll also give him recommendations for the best antennas. There's also TVFool.com.
Jim also wants to use a DVR with it. Leo says that TIVOs are still around and that would be the best option. Leo says he should go to Weaknees.com for it. Leo recommends the TIVO Roamio (base model) Series 5. It has 150 hours of recording, and it has a Netflix interface, so he wouldn't even need the Roku.