Build a Home Theater PC (HTPC) with a TV Tuner Card installed for your DVR needs. Use Windows Media Center, XBox Media Center (XBMC) or MythTV to control the DVR. How powerful of a system you need is going to depend on your wants and needs for this type of system.
I can't speak to scheduling the downloading of movies, though,
You cannot record content from Netflix, Amazon, Hulu etc... That's called Piracy and is not tolerated here at Tom's Hardware.
The Ceton and SiliconDust (as well as the Hauppauge WinTV-DCR-2650) are all cablecard devices used to replace the set top box from your cable company. None of these devices will aid you in streaming content from Netflix, Hulu, etal. These are "always on" type solutions. There's no need to "download now to watch later". Assuming you have a fast enough Internet connection, find a movie you want to watch and click play. Within a minute or so, you're watching the movie.
@Terry - there is no such device (just imagine if there was - big sharks would immediately attack it on DMCA basis). So, your best option would be a Windows PC, and searching for rigth software which can record streaming video. I am not aware of a software where you can schedule recordings.
These video services have compressed the video stream sufficiently to the point where, assuming you have a fast enough Internet connection (I think 3Gb/s is the minimum), you don't need to "pre-download" the movie. You sit in front of your HTPC connected HDTV. You browse Netflix (or other video service) until you find something you want to watch. You click play. Normally within 30 seconds, you're watching your video. Again, assuming you Internet connection is sufficient, there is no buffering involved. Your programming should not pause at any time while viewing it.
I have 4-5 times that minimum broadband , and I still get buffering (I have an internet connected HDTV). I want to use Windows Media Center. All I need is a tuner and I should be able to down load movies theoretically. The windows media Center is even all set up to configure a tuner.
My intention isn't to "cut the cables". I would like to expand my selection of video, and maybe reduce my DirecTV bill.
How is it connected? If this is a wireless connected HDTV and you're trying to stream Netflix (or other) over a wireless connection, what connection speed you have to your Internet modem won't matter. Wireless just isn't going to cut it.
I want to use Windows Media Center. All I need is a tuner and I should be able to down load movies theoretically. The windows media Center is even all set up to configure a tuner.
Satellite is a completely different beast than cable. You won't find a TV Tuner card that can accept a direct Satellite feed. At best, you can use the HDMI output of your satellite set top box to an HDMI input capture card. However, even a set up like this still will not capture movies from video services like Netflix.
How does your HDTV connect to the Internet? If it's hard wired to a router; connected to your modem, you should not be experiencing any buffering in movie downloads. If the HDTV is connected to your network, wirelessly, this is your issue. Either due to distance, obstructions, or just a plain bad connection, your HDTV cannot maintain a connection speed sufficient to stream video from a video provider.
It is a Samsung HDV connected by ethernet to the router and then to a cable modem. And yes it does still buffer. There is a 3 meter cat6 cable to the router. The direcTV DVR is also connected to the internet (by same network). I just measured the broadband, and it varied from 11.3 to 19.7 Mbps.
There's something messed up in your network, because with those speeds, there should never be any buffering when viewing media from Netflix, Hulu, etal. Just as a test, if you have a wired connection on your PC to your network, try watching a Netflix program on your PC. Do you still experience buffering?