I'm looking into buying a new dvd player and I'm thinking about getting a recorder. The one I have picked out is this Toshiba D-R400 Tunerless 1080p Upconverting DivX Certified DVD Recorder
I'm not sure if I need the tuner or not. I have an HD set top box and an HDTV. If I get this recorder with my set up what will that allow me to do and what won't it allow me to do. For example will I be able to program it so it will record something while I'm not home, will my TV have to be on, whats the highest quality it can record etc.etc..

I'm looking into buying a new dvd player and I'm thinking about getting a recorder. The one I have picked out is this Toshiba D-R400 Tunerless 1080p Upconverting DivX Certified DVD Recorder
I'm not sure if I need the tuner or not. I have an HD set top box and an HDTV. If I get this recorder with my set up what will that allow me to do and what won't it allow me to do. For example will I be able to program it so it will record something while I'm not home, will my TV have to be on, whats the highest quality it can record etc.etc..
While I'm not familiar with the Toshiba D-R400 some basics apply.
Without a built in tuner, it will only record whatever it receives
through it's input jacks, so to do a timed recording the source
(in this case your HD tuner) would have to be powered up, and
tuned to the channel you wished to record, plus you'd need to have
cord(s) hooked up from the tuner's Output(s) to the recorder's Input(s).
Whether the TV is on or not is irrelevant.

Just to add a little bit to what Chuck44 said, a DVD Recorder not having a tuner will be ok as long as your Set Top Box (or Satellite Dish, etc...) has the ability to change channels on some kind of a timer system. This way if you want to record more than one program, on different channels, while you are away, just leave your Recorder set to Line 1 (or whatever input you chose) and you will be able to record multiple programs.

Even if analog broadcasting is going away in 2 years, I think having at least a cable ready tuner for analog channels is a very very good thing to have. That is, while it's not certain, there will likely be some analog channels around long after the broadcast analog channels go away.. So being able to plug the cable plug directly in the recorder and record that way is useful, even if you *usually* record from the HDTV box.
(I record many things on my XS32 from my Tivos.. but I also record things natively with its tuner.)