I'm really new to AV stuff so excuse me if I'm way offbase:
I read that the 805 will convert signals to 720p if the video signal processing is turned on. You can turn the signal processing off and it will just pass through the video signal. So it would seem that you would want any 720p or greater signal to be passed untouched through the 805 to your HDTV and let the HDTV handle the signal.
In the case of a standard analog signal (e.g. standard def satelite broadcast) you should have the 805 upconvert that to 720p to get a cleaner picture than just passing directly to the HDTV.
BTW... if there is a good AV primer that covers these sort of topics feel free to drop me the link.
My situation: I'm looking to buy a 50" 1080p plasma. I will be buying a new non-HD DVD player. My wife and I will still watch plenty of standard def TV shows from our satelite service (I've heard stories of standard def signals looking terrible on HDTVs). I also watch sports that ocassionally come in 720p and 1080i varities. How does the 805 help us with the video signals in these different situations?