Correct, you can expand or clone/mirror whichever monitors you'd like. UltraMon does this very easily. Windows can also do it to a slightly lesser degree from within Display Settings.
And I'm gonna take a guess and say that 8bit has never used a multi-monitor setup. Believe me, when you use a multiple monitor setup, you won't want to go back. For everyday use, there are tons of reasons for two monitors. I can also see myself using three for use with photoshop, frontpage, etc.
While I will agree that 4+ monitors may not be worth it unless you have a real reason for it, don't knock multiple displays. They are absoultely great, and once you get used to them, you won't ever want to use a single display again.