I apologize in advance if my questions were answered elsewhere on this thread but I could not find definitive answers.

My components include the Pioneer Plasma TV PDP6010-FD, Toshiba A35 HD DVD Player & Onkyo TX-SR605 AV Receiver. I plan to connect the HD DVD player and a HD DVR to the receiver via HDMI cables and then connect the receiver to the TV via HDMI cables in order to take full advantage of the audio and video capabilities of each.

For the HD DVR I have to choose between DirecTV models HR20-100, HR20-700 & HR21-700. I understand that the major differences between the HR20 & HR21 are the following:

1.) HR21 does not have OTA tuners and so I will not be able to view/record my local channels in HD since DirecTV does not broadcast my local channels (Richmond, VA) in HD

2.) HR21 has an extra ethernet port, but not sure what this would be used for since you would use a single one on the HR20 to connect with your home network

Here are my questions:

1.) Other than what I listed above are there any other differences between the HR20s & HR21s that I should be aware of considering my other components?

2.) I have read differing information as to the HD recording capacity of the different models. Is there any difference?

3.) What are the differences between the HR20-100 & HR20-700?

4.) If I am okay with not receiving the local stations in HD would I be best off just getting the latest - the HR21?

5.) If getting/recording the local stations in HD is important to me does that necessitate getting the HR20 or are there other considerations?

6.) If I get the HR20, which model do I go for, 20-100 or 20-700?

7.) Assuming I go for the HR20 model, will I need to connect a separate antenna to the DVR in order to receive the OTA local HD channels?

Thanks in advance for your help and advice with these questions.