It has to be a Plasma, or at the very least a very expensive LCD type.

Your viewing distance is typically closer to a computer monitor than a tv and I'm sure we're all familiar with watching a cheaper lcd at the wrong angle.

If you're all of 3 or 4 feet away from a cheap 42 inch lcd then the chances are great that the rather sharp viewing angle off to the sides and the corners with distort/shade/discolor those parts.

On the whole though the idea does appeal to me. I have been a tri-monitor user for a number of years now and it's a pain in the butt. But then multiple monitors was really the only way to go since large screens (up until recently) were quite expensive. When it's time to re-new I will most likely go with one large screen to simplify the work area as well as screen calibrations and such.

I should also add that some fairly major adjustments will most likely have to be made to your work area. A 42 inch screen (for example) would have to sit LOWER than the desk surface so that your eyes would better line up with the center of the screen.

I'm using the Panasonic Viera 50" full HD plasma as the secondary monitor for my edits. It is hanging above my system monitor (24"), tilted downwards; the watching distance is just above 1m.

With my XDCAM EX material (not to mention 100 Mbps, 4:2:2 from NanoFlash), I find it just great for level and color correction.

second monitor been a 32 lcd hdtv for a couple a years.. works very well for me

I have been a tri-monitor user for a number of years now and it's a pain in the butt. But then multiple monitors was really the only way to go since large screens (up until recently) were quite expensive. When it's time to re-new I will most likely go with one large screen to simplify the work area as well as screen calibrations and such.

biggest issue with that is that a 52" HD screen is 1920x1080 res. 3 19" LCD's can be 1440x900 each, giving a total resolution of 4320x900 wide if you wanted. All you're doing is making the pixels bigger with a bigger screen, not increasing resolution. ~2million pixels with a HDTV setup vs ~4million pixels with the cheaper, smaller, multimonitor setup. Your best bet would be multiple projectors, but that would be expensive in initial setup & maintenance costs.

EDIT: if you're using the TV as a monitor & not a preview monitor you just need to hook it up. No need to even change any settings.