I am considering getting a Hauppage 1212 External PVR
Top quality for video is 13.5 MBPS.
How much space would a half hour TV program in HD take up?
I am considering getting another external hard drive just for the PVR.
Sounds about right. My 1 hour 1080i HD recordings are ~8 GB so I expect a 30 min program should be about 4 GB, depending on the bitrate. Blu-rays can vary in bitrate up to over 40 Mb/s as they (1080p source) have double the frames as 1080i (I think?? )