When they're referring to the built in NTSC tuner, that doesn't have anything to do with your cable. That affects OTA (Over-The-Air) HD reception, which you can get for free if you have an antenna (think old school rabbit ears). Basically they're saying that your TV can get HD reception out of the box without having to buy anthing extra (besides an antenna).
I live in the LA Metropolitan area and even where I am, HD reception via OTA sucks. If a certain channel comes in clearly, another channel won't and vice versa. I'm sure you remember how much rabbit ears sucked before cable boxes came around.
Here is what you're interested in:
Connectivity
Number of AV connections : 2
Other connections : F-Type (75 ohm), PC Audio in, DVI-I
AV 1 : Audio L/R in, YPbPr (2fh)
Front / Side connections : Headphone out
AV 2 : Audio L/R in, CVBS, S-Video
Basically you have 3 ways of video input.
#1 is DVI-I
#2 is Component (Red, Green, Blue for video) + (Yellow+White for audio)
#3 is S-Video (S-Video + Yellow+White)
To really make use of Hi-Def, you want to use at the minimum a Component connection. S-Video would be pointless to use unless it was for an older video game system or a VCR.
I'm no tech expert and I haven't looked into LCD TV's too much lately, but you might want to find one that offers an HDMI input with HDCP. From my understanding, HDMI is basically similiar DVI (digital connection) but with audio on the same connection, but the reason why I recommend you looking into making sure you have HDMI w/ HDCP is because you want to make sure your TV is future proof. HDCP allows them to control digital copy protected content.