You want to keep your computer on at all times, so that people can log on and do their turn, but each complete turn is automatically backed up so in case of a power loss you can always reload.
The only issue is the fact that only complete turns are being saved automatically, so if player 1 completes his turn, and player 2 doesn't, then if you lose power, and have to reload - player 1 will have to re-do the turn. The best thing to do, if you know you'll be shutting down your pitboss server, is to manually save the game from the pitboss dialog - you get no loss of information then. Also each player can manually save the game on their local machines, and send that save to you in case you need it.
By the way - the problem with saving is only present in Simultaneous Turns games, but that's the setting you'll be most likely to play with. Regular - Turns Based games don't have that problem, as a save is being made after individual player moves...