I doubt that will look decent. First TVs are not monitors. Remember that the pixels are spread out over a greater area, so everything will be huge compared to a proper monitor.
If you insist, then buy a set with HDMI or a DVI port. VGA is definitely NOT the connector to use. Also, only consider buying a 1080p TV. Nothing less!
It is not the size of the monitor that determines if an OS can run it. It is a matter of some standards and to what resolution the OS and the video card can handle.
The Apple 30" monitor has a much higher resolution than any TV you could buy on the common market right now. A 1080p TV can display up to 1920x1080 pixels. The 30" Apple display has a resolution of 2530x1600. Of course I wonder how good a TV display it would be, since you would have to up scale a source to use the full display.
As you can see, a Mac Pro will easily handle your TV. You might need an adapter.