It all comes down to panel quality, and although some TVs look amazing, it's doubtful they'll look as good as a quality computer monitor. One thing to consider, is that on a large TV, the actual resolution is lower than what a decent computer monitor will provide, usually 1920x1080 or less. Because it's so much larger than a computer monitor though, it's pixel width increases drastically, which will degrade the crisp image.
Thing is though, when you sit 10ft back from the TV, you're not really going to notice this. But running a PC on the same TV, you probably would. I'm certainly no expert on the subject, but that's how I've come to understand things. Ideally, the smaller the pixel width, the crisper the image. You just can't get a small pixel width on a large TV though, unless the resolution actually scales (and on the computer side, we don't have any consumer products that exceed 2560x1600 yet).