There are three important things to note about the use of an electronic device.
First, the computer itself does not teach your child. If the software has reinforcers built into the games or activities that you purchased then this might work. However, if your child does not like the particular reinforcer in the program then the child will not learn. For example, if your child likes music and the reinforcer in the game is music delivered for a correct response then the child will not learn. Before purchasing a game it is important to look at the game and see if the reinforcers are included.
Secondly, it should be noted that many games are specifically designed to include reinforcers and many are not. Some are based on psychological research including games such as those developed by "Headsprout" ( recently purchased by another company) and many others. Parents should read and look at the information about the games to see if they are based on research or psychological principles such as reinforcement.
Third, parents should also consider the skills taught by the electronic device. Are these skills you want your child to learn. There are games to learn most anything such as spelling, reading, self-care skills, morals, social skills and much more. I contrast it should be noted that children might model some behavior in games and there is such discussion and research that indicates that some aggression can be learned from modeling of television or games. This should be considered in your purchase of a game. Games your children might like might have some benefits and some deficits in their affect on your child's' behavior. All of these factors should be weighed and considered before purchasing a device and programs for your child.