Originally posted by: andre1rocha
you have to buy a hdtv tuner! not just plain tv tuner.
HDTV tuners let you get over the air (and with some, like the HD Home Run, QAM-based digital cable) HD channels, it's true. And those channels will come across in a much higher resolution, typically 720 lines progressively scanned, or better. But that's still only a few channels, and without an STB its just the network rebroadcasts that the FCC requires the cable provider to transmit in the clear. Everything else, ESPN, Discovery, INHD, or whatever, is encrypted.
Someone asked about resolution. NTSC formats that you get through tuning standard VHF or UHF television signals generally provide around 720 columns by 480 lines. Considerably coarser than even 800 x 600, which most people consider to be low resolution these days. It really doesn't matter how high res the monitor is, as this simply means more than one monitor pixel is used to construct a single pixel from the frame. It more or less looks just as blocky on a CRT television in the family room as it does on a CRT or LCD monitor in the office. What makes the set in the family room look a bit better is: a) it isn't compressing the video through MPEG; and b) it has analog color response. There are no colors it can't display. Well, from a technical standpoint there are, but compared to a digitally reproduced image the color depth is essentially infinite.
I have a 550-Pro based tuner card from ATI, and using Beyond TV 4.6 with the Intervideo MPEG-2 codec, the quality is more than acceptable from the distances I view it at. That's another thing worth remembering: if you're sitting at the desk watching it, you're much closer than you generally would be to the set in the family room. Go stand close to that, and it will look like crap too.
Bottom line: there is only so much data in the NTSC signal to begin with, then you lose some of the color information in digitization, and then lose more information in compression. I would just sit back and lower my expectations a little

. On the other hand, if it really bothers you (and it probably bothers you when you watch DVDs on the comp too), then you can play with tools like ffdshow and try to get a nice upsampling pipeline running. The results can be impressive, but not usually across all sources, the setup is complex, and the upsampling takes a buttload of CPU.