Do you have a set top box hooked up to you TV tuner card on the PC? If no you need one to receive the channels with Fios.
Not entirely true. If the tuner you are using is QAM capable you should receive the digitized SD version of your local stations, your local digital (OTA HD) stations, the music channels, and the PEG stations. If it doesn't have a QAM capable tuner then the statement from Telcoguru is correct.
You don't get al the channels with QAM that's why I didn't mention it.
Just trying to give a little more accurate information. The implication in your original post was that if you didn't rent a box from Verizon then you can't get anything (or at least that was my interpretation) and that is false as I stated earlier.
Now the question is what difference is between Verizon FIOS tv and Comcast digital tv? Using the same tuner, why I could receive some Comcast channels but not any FIOS channel? Both cable services indicate that the local channels are not encripted.
The difference is that even though you had Comcast Digital, they actually have a hybrid system with analog (old NTSC) channels for some of the basic cable channels as well as your local SD broadcasts in addition to the digital channels. Verizon is (or is in the process) of migrating to an all digital system so your old "Cable Capable" tuner (which is analog) has nothing to tune - you must have a QAM capable tuner to tune any of Verizon's channels, and then only the limited subset I mentioned in my earlier post (no national stations other than WGN, only locals).
Hope that clears up the confusion.