60+ is good, anything higher than that you won't notice. Anything lower than 30 is considered unacceptable as you really feel the slow down with any fast games (FPS, etc). Some slower games, like Oblivion (RPG), can still be played fine as low as 20. A TBS may be able to go lower just because the action isn't as important as the moves you make, but that should be enough information for you.
Post 400!