I went to the Comcast office on North Ave. on Saturday morning with my Comcast DVR box. In about five minutes I traded my DVR for two cablecards. When I got home and set up my TiVo HD, I put one card in (as instructed). TiVo recognized the card as a Multistream card and instructed me to not put in a second card. Being curious, I saw that I could receive maybe about 20 low-numbered channels. I then called Comcast to start service on my new card. After about 30 minutes of attempts, placing on hold, etc. I did not get any service initialized. I was told that a higher level tech who specialized in this sort of thing would call me in about 3-4 hours. After 5 hours, I called them back and was informed that they had scheduled an on-site technician visit for me on Monday. Mind you, they never informed me of this! How would they think I should know to be at home for this automatically scheduled visit?? Very frustrating. On the plus side, she said she would give me some sort of credit. Not sure of the amount, though. So anyhow, a technician came to my place this morning and after about 10 minutes of reading in settings to the main office, my channels began to come in. Interestingly, he said that both cards had to be in the TiVo, even though one is a multistream card (the second card is not). He didn't really explain why that is. (Does Comcast not yet support multistream cards yet?) He also said that the cards were assigned to my account but not activated at all. So whoever I talked with on Saturday did not know what they were doing. The technician then told me how, in his opinion, he did not like cablecards and much preferred cable boxes. Normally I would have debated this, but I just wanted everything fixed so I could get to work. Long story short, it was a bit of a hassle. I think if you are debating whether to do a self-install or have a technician come out, you may want to err on the safe side and just schedule a visit. Hope this helps anyone thinking about getting TiVo HD in Chicago.