Punta Cana can be a good place for windsurfing. If you are seriously interested in windsurfing, you should know that the Mecca of wind sports in the Dominican Republic in Cabarete (about 8 hours drive from Punta Cana from) located.
Usually windsurfers use a 5.5m sail and 100L board. You should be able to get the equipment in the watersports center at your resort, but since this is not the most popular sport here, you should try to check at your hotel in advance if this is available even before you arrive in Punta Cana.