It does somewhat rely on how many graphics cards you have, depending on what you want to do on multiple monitors. To play games on multiple monitors, you usually need 1 card for 2 monitors, and 2 cards for 3 monitors. If you don't want to play games, there are many options for multiple monitors. The largest number of monitors I have heard of being hooked up to one computer is 16, although I'm sure a larger amount is possible.
Practice makes perfect and nothing is perfect, so why practice? -brektzar