PVR = Personal Video Recorder.
DVR = Digital Video Recorder.
TiVo= beats the hell out of me, but a registered trademark.
The Visionsat has a USB connector, where you can plug in a user-supplied hard drive up to 500gb.
Shows can be recorded while away, played back over and over, skip forward or backward.
And, by plugging the hard drive into your computer (with the right simple software tools), you can make the shows into playable DVDs.
I have a tiny 60gb drive, which I use as described, and I'm quite happy.
300 and 500gb external USB drives go on sale for under $100 at every holiday, so by all means get a big 'un. -
edit: oh, and I forgot,,, at least with the Visionsat, you can plug in a 2gb or bigger thumb drive and get similar capability.