i would've thought the phrase "white box" would be more or less reserved, as it's a portable keypad/phone dialer (if memory serves correct) in phreaking circles.
Just Google up "Linux PVR" or something similar. If you've got parts from an old PC, costs should be minimal. There's also the simplest method; getting a tv tuner card like Grey Ninja suggested. You won't have a dedicated PVR, but it's quicker and cheaper than building one.