Over the holidays I came across a Foxconn nettop box and a SiliconDust HDHomeRun Prime. That looked like the parts I needed to start with.
Since the Foxconn system was barebones I put 4GB of RAM and a 500GB HD in it and installed Windows 7 Professional expecting to run Windows Media Center (WMC).
I started with the HDHomeRun Prime setup. It references WMC so I just played along for now.
I may still get to WMC but it is so much bigger than I need and I keep bumping into problems (mostly of my own doing).
WMC is a tremendously rich solution but I just want to record TV video just like I did with the SageTV. WMC is expecting to be a complete media center and therefore is picky about its video capabilities. Even with the latest drivers for the Intel video in the Foxconn system it wouldn't pass WMC's tests. I found that I wasn't the only one with this problem and there's even a registry hack that overrides WMC's check. That got me to the next step but WMC still complained that there was a "serious problem." I expect that that is because I'm using a VGA monitor not an HDCP compliant HDMI monitor.
As I don't really want to watch video on this system I moved on.
I found NextPVR and that seemed to be a good fit. There is a good article on Lifehacker and a follow-up blog here. After you download and install NextPVR be sure to load the patches before you start NextPVR even for the first time. Otherwise you'll have to go into Windows TaskManager and kill off the NRecord process to get the patched DLLs to copy.
There was a saga with Comcast and the CableCARD but that's nothing new. This thread on SiliconDust's forum was a huge help. Read that closely as one of the contributors notes that CableCARDs don't "scan" for channels but rather get a "map" from the provider. If you want the clear QAM channels as well you will need to scan and I did that before I inserted the CableCARD.
Comcast seems to send all the video down in MPEG2 format with AC3 audio. I used the Microsoft DTV-DVD Video Decoder and installed the LAV Filters for audio decoders.
Getting a program guide working is my next challenge.