A TV set is not a monitor. It has none of the clarity, resolution, or stability to display static pictures such as fine lines and extreme colors of a monitor. If you want to use it for movies, that would be fine, but you need to understand that a TV set is not just an inexpensive monitor, you are giving up substantial quality to use it as such.
Mac Pro 65 lb tower can connect to display devices by DVI, Mini DisplayPort, DisplayPort, HDMI, and in a pinch, VGA but that is really a bad compromise. You need adapters for some of these, and ACTIVE, POWERED adapters to use three displays off an AMD/ATI/Apple card.