Edward has been trying to learn more about HTPCs (home theater PCs). He wants to make an old PC into a DVR. Leo says that copy protection is often an issue with this, and cable boxes are encrypted to prevent people from using their signal that aren't paying. A computer can descramble it with a cable card, but cable companies aren't that helpful with using them. They have to give you one by law, but they don't like it. The cable company pretends they don't know anything about it, even though it's been the law since 1993.
All too often, if your cable company has a store front, you'll have better luck going there than calling to get them to help. Then you have to be sure your hardware supports it, your capture card supports it, and your OS supports it. That's why Leo recommends just getting a TIVO.