I also used four computers from a neighboring class for one session. These were used for Internet research purposes. I would suggest letting desires and wishes known to your supervisor. Sometimes equipment is available that only administrators are aware of. Attending conferences can be helpful in locating ideas and resources.
Internet searches are great sources of information.
This varies with the age and composition of the class. PC- Four worked out o.k. The quality of each individual slide depended on the ability of the student. I really liked the amount of computer technology each child received. I would have to say they enjoyed learning how to use the digital camera.