I went through 3 Toshiba 36HF71 sets before giving up... set #1 arrived with the center 3/4 of the screen very very dark, color casts on the left and right sides of the screen (different on each side), the screen would never go black but hit a medium gray and show magenta raster re-trace lines, periodically the screen would flash white and over the next 15 to 30 seconds settle back down to normal (still all screwed up of course). Set #2 not focused well and a moire pattern on the left 30% of the screen and the right 30% of the screen. Stars or thin vertical lines in the areas where the moire pattern existed would shimmer and change color if they were in motion (camera pan or whatever). Toshiba claimed it was a defective shadow mask. Set #3 - focused well, but still had the moire pattern in the same areas (not obvious all the time, Onkyo's dark blue menu background made it highly obvious though, looked like wood grain. Image always grainy looking in moire areas - again, stars and thin vertical lines shimmer and change color if in motion... and even stationary convergence test patterns showed some shimmering in the moire areas.
I ended up buying a Sony 36XBR450 which I'm completely happy with. Digital cable usually has the first 100 channels analog to maintain compatiblilty in the system so if your analog cable looks bad, going to digital cable will get you the same problems. The Sony is fan-freakin-tastic on local stations received over the air by antenna. The same local stations are on the analog portion of "digital cable" and are OK, but not great. The digital channels on digital cable (100 and up) look better than the analog channels but it is easy to see digital compression artifacts around text that is on top of images. If you have digital cable, your provider may offer High Definition channels (HBO and Showtime at least) - I get the HD digital cable channels and they are remarkable, mostly, when they send 1080i which is only about half the time right now. There are NO visible artifacts of any kind unless there is a 'blip" that causes the picture to make obvious pixel blocks for a split second.
Why bad video looks bad on the Sony HD sets... their DRC doubles the horizontal and vertical resolution. Most HD sets double only the vertical resolution to eliminate visible scan lines in the image. So any defects in the image are magnified more on the Sony than on other HD sets using line doubling only. The result is that on high quality "old" channels, the Sony looks excellent... but the worse the image you ask it to reproduce, the more you will see the problems in the image.