Planning HTPC with HD PVR and DCT6412

[harlekin]

I am in the planning stages for a HTPC and would like a bit of guidance on a couple of details. The rough setup that I expect is as follows:

Generic PC (components I have laying around, should be fast enough)
Motorola DCT6412 III (Comcast/TWC - Comcast sold the region to TW, so the setup may be a bit odd. It had working Firewire last time I played with it, but could be broken now via software updates)
Hauppauge HD PVR (I want premiums and On-Demand to work)
Analog Tuner card (for rudimentary dual tuner support at least)
SageTV, most likely using SageMC
HD extenders

The functionality that I am aiming for is to archive my dvd collection for easy playback, digital TV and DVR, on demand, and music, all available from three rooms using a couple of extenders. None of my TV's are HD currently, but I'm trying to be somewhat futureproof without spending too much money yet. I would like to use Firewire for control (rather than IR) if possible, but may be limited by my desire to access VOD services.


My main questions are these:
Can firewire be used to control the DCT6412 beyond just changing channels? In particular, can it be used to control the VOD menus?

What analog tuners are recommended? PCI/PCIe preferred, USB would be passable. A dual tuner card would be a plus.

Have I overlooked anything important in my hardware?

Does anyone have any experience with setting up On Demand through SageTV?

Any other suggestions on hardware or features that might be useful are appreciated.

[paulbeers]

Last I knew, On Demand was not possible thru sage as the IR blasters only only created to send numbers. You would have to find some way to send a "select/enter" command. I guess I shouldn't say it isn't possible, I suppose there are ways, but it would require some programming know how.

[harlekin]

I've seen mention in a couple of places on the forums to various levels of success with on demand. I am comfortable with some light programming to glue everything together. I think the guy who had it working well used Girder, so I'll probably look into that. I don't know whether I will be able to get On Demand working through the extenders, but it should be workable on the primary at least.

[harlekin]

I should also point out that I have a harmony remote that I can use in this setup. Is there anything special that this adds to the equation?