Water is always fun to photograph, it lends itself to a whole raft of techinques, and expressions. From very fast exposures which slow or freeze the water, to long exposures that give a misty erie cloud like flow to any motion, to reflections off the surface or images from within.
The good thing about fountains and water sculptures is that they are both dynamic and predictable, which gives you the opportunity to try a gamut of effects or techiques. Freezing the action with very fast exposures is probably the easiet, though if you have a tripod or some way of stabalizing the camera, then long exposures can result in some brilliant imagery.
For fast I would say you need at least 1/500th sec, preferably 1/1000th. And whilst this problaby means a wide aperature to get the necessary exposure, with fountains and water sculptures you know where you need to focus.
For slow I would recommend 1/25th to 1/10th depending on the speed the water is moving.