I like the Silicondust stuff, kind of what my currently dead Slingbox should have been, and way cheaper. If you go to their website,
http://www.hdhomerun.com/ they have a page that will list all the clear qam channels by zip code and cable provider, around 80 for me including HD dups, worth a single tuner at least to me.
I hate my cable DVR ***, but its still the best option, and given the long history of the cable companies resisting and causing problems for alternate devices, I want to see anything new work for a few months before jumping on new technology.
*** I hate it, but you'll pry it from my cold dead fingers, whole family is totally hooked on time shifted viewing, blipping past commercials, and FF, pause, etc watching.
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Current plans
I bought the spdif expansion panel bracket and cable for my motherboard, an ATi X1300 PCIe video card with S-Video output, bid on a Silicondust dual tuner, but lost and likely will pick up a cheap ATi HD600 tuner card for qam and S-video input. Once I replace the old S-video crt, system will get revised with HDMI.