The basic important piece of non-standard PC hardware in a Myth Box is a TV Tuner Card. This is the board that hooks up to your cable or antenna and decodes and captures the video signal from the channel you want to record.
Analog framebuffer cards
Analog Hardware-MPEG cards
These cards, currently the Hauppauge PVR-250 and Hauppauge PVR-350 and the AVerMedia M179, have a video processor onboard which compresses the tuned video signal into an MPEG-2 program stream before sending it into the computer. The tends to greatly reduce the load on the entire machine (with certain technical caveats), and these cards are recommended for.. well for all systems, really, but specifically, for systems with more than one, and especially more than 2 tuner cards.
Digital Hardware-MPEG cards
Like the Analog Hardware-MPEG cards above, these cards have a video processor onboard which compresses the tuned video signal into an MPEG-2 program stream before sending it into the computer. One example of such a card is the AVerMedia DVB-T 771.