powers7977,
NTSC will be ending transmissions on Feb 2009. The new spectrum will be ATSC. QAM is for descrambling cable channels.
ATSC is the new "rabbit ears" over-the-air transmissions that will replace NTSC.
Does that answer your question? If you have more, let me know.
--HDTech
The specs for the 550 & 630 the two tv's I'm considering state they only have ATSC & Clear QAM tuners built into them. But what about NTSC for SD channels? We only have access to SD channels so how will that work? I'm an extreme novice when it comes to the LCD TV technology!
Thanks so much!

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