Guys, are you actually listening to him at all?
You don't want to use the internal PVR. That's fine. You can use your existing DVR.
You will need to use a USB UIRT, to control your cable box and other existing TV equipment.
You will also need:
* Xantech 286 double emitter
If you intend to digitize this signal, to bounce to other media directors in the house, you will need a supported tuner card. Right now this means Hauppauge PVR 150/250/500/USB2. We do not have support for the Hauppauge HD-PVR yet, but it will be coming in a later release.
You then need to affix the emitter nubs to each of your AV devices you wish to control.
And then make device templates for them in the web admin. The device templates tell LMCE about your devices, and in the case of AV equipment it describes the commands the device can handle, as well as any inputs it may have or provide. Your TV has inputs for HDMI 1/2/3, and/or Component, etc.. This will allow LMCE to understand what you have.
Once you make device templates, you can then use the setup wizard to select your AV devices, and tell LMCE how they are connected together, in which input ports etc. LMCE will use this information to send IR pulses to the relevant gear to switch inputs, etc.
I haven't mentioned RS232, because it's not as common, but it is a much better option if it is available on your equipment, or you can get AV equipment with RS232 ports, because LMCE can not only more reliably control these devices, but also they are bi-directional, so changes to them can be reported back to the system and dealt with automatically.
If you decide to connect the device to a tuner card, the signal can be bounced automatically to other media directors in the house. In the case of the PVR 150/250/500/USB2, just connect the s-video and rca audio from your cable box to the tuner card.
Once this is done, LMCE will generate a scenario button, which will bring up a remote to control the device on any orbiters you may wish to use, and any remotes attached to a media director will be able to control the cable box etc automatically, while sending commands to the correct devices (volume goes to amp, display power goes to TV, channel goes to cable box, etc.)
If you do not wish to use an HDHomeRun or use MythTV (aka the TV scenario), then don't use it, and simply use the LiveTV scenario, however, MythTV has many features not available on commercial PVRs and is more flexible. Any recordings made by it show up automatically in Videos, and are available to all media directors in the home.