The most important issue to note is that while the HD PVR will work on a standard def TV, and while it does have superior hardware (bigger hard-drive, better scaler, faster processor etc), the software is way behind the SD PVR. It is unstable, buggy, recordings often get lost, and it lacks many of the features of the SD PVR. What makes up for all of this is the awesome picture quality of the HD channel. The bugs will get fixed with software updates (apparently a big one coming in the next 2 weeks or so). But your folks may end up being disappointed with the buggy software, and not having HD picture quality to make up for it.