Windowsmedia setup issue, XBox extender, IR remote

I am having an issue setting up windows media center on my computer. I am running windows 7 ultimate and have set up an xbox 360 as an extender in another room.
I have been trying repeatedly to get this set up and keep coming up with the same result. I get to see the channels that I receive through a set top box from Comcast, which is an HD/DVR also. I get to see my channels the way that I ought to on my WMC guide but cannot change them, either through the remote on my PC nor on my xbox 360 in the other room.
I can view the channel that my set top box is set to but have to change that via my STB remote from Comcast and therefore if I am in the back room and I want to see another channel then I have to come out to the living room area and change the channel which defeats my whole purpose of having an extender in the first place.
The Hd/DVR is a Motorola and I have tried the set up in WMC and nothing seems to work.
The channel that I am viewing via the xbox 360 is perfect with no other issues than not being able to change the channel.
The guide shows me the channel that I want to be changing to and gives me an updated guide view but it is the screen itself that just remains on the STB channel.

Please provide more details about your hardware setup and arrangement. Cabling, tuners, network layout, etc.

Do you have a Ceton tuner card in your HTPC? Do you have an OTA/ATSC tuner card? Silicon Dust HDHomeRun??

How are you feeding your Comcast cable content to your HTPC? What does WMC think you have for tuners, and channel-selection?