Imagine my surprise, then, when they actually showed up. An hour into the 3-hour window, but it could still be considered "on time". He didn't know anything about the tuner card, so he let me install the CableCard and take care of all of the other steps while he called in the numbers that Comcast needed. Once things were synced up, I was able to successfully tune a few channels, but not all that I expected to get (missing were mainly HD and premiums). He left, as we were both thinking that it might just take a bit of time for those to show up. They didn't, but a quick call to Comcast sorted things out and minutes later I had all of the channels that I was paying for.
My TiVo replacement is finally up and running!
Granted, a better choice for a screenshot might have been either X3 or The Two Towers, but I can't do a full-screen Windows Media Center screenshot and those channels won't display in a window... blasted DRM.
After getting that set up, I installed software for channel logos and web-based scheduling, neither of which would work without a TV tuner and guide data being set up first. The latter is currently disappointing in the fact that it doesn't honor WMC defaults for series recordings, but the developer is apparently looking into it.
If the next couple of weeks of testing go well, and at the moment I don't have any reason to believe they won't, I'll be wiping and deactivating the TiVo and returning the 2 CableCards currently in it. At that point, the HTPC upgrade should start paying for itself (aside from the part covered by my year-end bonus), to the tune of around $23/month in savings.
Having 4 tuners instead of 2? Icing on the cake :-)