You cannot connect one DVR (a TiVo, for example) to another (a DISH PVR, for example).

I'm not sure what you mean by that. Before I got my HDTV, I had my Dish cable input to my 612 DVR, the 612 was output into my Tivo and then the Tivo was connected to the TV and I could record on either one, and watch what was recorded on either one. The Tivo remote and the Tivo IR controlled the Dish 612.

Mike

Well I believe I have answered my own question. I have connected my Dish DVR to my Tivo and it all works just fine. I have the Dish VIP612 DVR (dual tuner) feeding HDMI to the TV and SD to my DVD player. The DVD player feeds to my Tivo. The Tivo then feeds SD to my TV. I also have an indoor antenna feeding the ANT input on the TV. I switch from Tivo/DVD to ANT to Dish inputs by hitting my INPUT button on my Dish remote. So far I believe I have established that I can schedule and record SD onto the Tivo - it will control the channels on my Dish DVR tuner TV1. I can watch HD on my TV from the Dish DVR and record HD onto my Dish DVR to tuner TV2 while watching and/or recording SD onto the Tivo via tuner TV1. I can play DVD's to the TV through the Tivo in SD and I can record DVD's onto the Tivo while watching them, or while watching an HD show via the Dish DVR. And I can download Tivo recordings to my laptop over my home network to take with and watch when I travel. So I guess I will keep my Tivo for a while longer.

One other point. I have one ethernet cable coming through the wall into my bedroom where I have the Tivo and Dish VIP622. This cable on the other side of the wall is in a closet and plugged into an ethernet port on a Netgear wireless print server. The print server connects wirelessly to my Linksys G wireless router. I plugged this cable into an old Netgear 10/100MBPS ethernet switch and have both the Tivo and Dish VIP622 plugged in and online through the switch. Both can be controlled now via the web, and both "call home" via the internet. Glad I threw the old hub into a box 5 years ago and hung onto it.