FYI... I have learned some things from replacing my old Comcast set-top box and Series2 TiVo with a new TiVoPremierXL4 and Comcast-provided CableCard, and thought I'd share them. The TiVo+Cablecard installation was relatively easy, tedious, and ultimately disappointing. I'm a tech professional, so take "easy" with a grain of salt. Here's what went wrong: 1) Triple-play/Digital Premium Comcast subscribers may lose the "Digital Basic" channels (in Santa Cruz, CA, those between 34 and 65), including AMC, FX, USA, Comedy Central, A&E, CNN and other favorites. "Sons Of Anarchy" and "Daily Show" fans, take note!!! The knowledgable Comcast tech who just left confirmed the TiVo tech support conclusion that our "Digital Basic" channels are actually broadcast as analog signals. The TiVo/Cablecard cannot receive analog, period. No matter what the nice ladies in the Philippines tell you, the local cable plant may be hybrid. Assuming that's not a deal-breaker for you, or that you live someplace that all your "digital" channels are, in fact, digital... 2) The Comcast "self-activation" website took 3 days to detect my new TiVo/CableCard setup, so don't bother. 3) Do NOT call the number shown on the setup menu on the cable-card menu, or on the printed receipt for the cable-card; they're clueless. Call the 877-405-2298 hotline instead, and talk to the nice ladies in the Philippines call center. 4) Yes, you do need to cycle thru the "Test Channels" screens, pausing a few seconds on each, to figure out what actually got activated. A lost msg to the cable-card can cause some of your services to go missing. As others have said elsewhere, the incidence of missed enablement signals seems pretty high, and if your box isn't authorized by the head-end, you do not see the channels, period. If they tell you to wait an hour, you're hosed. Pull out your cable-card, power-cycle the TiVo, reinsert the cable-card, and go thru the whole Guided Setup + call Comcast for activation again. In my case, I think I needed to do it 3 times to get past all my issues other than the one involving analog "digital" channels. 5) As hokey as it seems, the THX training clip shipped on the TiVo HDD was really useful in getting a great picture from our Toshiba LED display. Yes, you need to wear the funky glasses; just make sure your kids aren't in the room with their iPhones and posting pictures of you on FaceBook. So, before buying a new TiVo Premium XL4 for use in Santa Cruz County, CA, make sure you're in a service area where these channels are broadcast as digital and not analog. Only you can decide if simultaneous record is more valuable to you than the missing "Digital Basic" channels. For us, it's not; I'm off to the local service center to swap my 4-channel cable-card for a stand-alone HD cable box.