Here's some info for people adding Comcast DTA converter devices to a TV setup using a Windows Media Center PC.

It's based on an exchange with a Seattle guy having trouble getting his new DTA converter to work with his PC. As he describes it:

The DTA worked fine on my TV. It was really actually easy. I tried to put a DTA on my Vista computer and failed miserably. For some reason the IR [infrared] blaster would not transmit well and Media Center would not recognize the signals. It tried to learn my remote over and over with no success. I went online and found other people with similar problems. Their suggestions revolved around moving the IR blaster around but that didn't work for me. It should have worked, but didn't. I already rent one DVR from Comcast, but I am trying to avoid renting a 2nd.

I relayed the question to Microsoft's Entertainment and Devices division, which is responsible for Media Center. The response from a spokesman:

Some Comcast DTA converter boxes use the IR code C1982, which consumers can select using "Find from List" in the IR setup. However, this code may not be applicable to all Comcast DTA converters. Microsoft MVP Barb Bowman has also published a detailed description of the DTA setup, which goes through the steps required to use a Comcast DTA with Windows Media Center, which you can find online here: http://digitalmediaphile.com/index.php/2009/04/17/setup-a-comcast-dta-with-mce/

Here's some earlier info I received from Comcast on how Media Center PCs are affected by the cable company's digital switch. Let me know if there are other ways to make these things work.