Schools in the U.S. spent $22 billion on hardware, information technology services, and software in 2003. Test scores have risen modestly since the introduction of personal computers back in the 1980's. In 1984, the average reading score for 9 year olds in the U.S. was 211 (out of 500); in 2004, it was 219. For math, the average score for 9 year olds in 1982 was 219; in 2004, it was 241. How much of the gains are attributable to technology as opposed to other factors is unclear.
A new study just released by the National Center for Education Evaluation and Regional Assistance (the research branch of the Department of Education) found no improvement in achievement test scores in classrooms using reading and math software products than in classrooms without the new products.
Dr. Jane Healy wrote an eye-opening book called Failure to Connect: How Computers Affect Our Children's Minds and What to Do About It back in 1999. It is a powerful critique of how computer use is developmentally inappropriate in young children (under the age of 6 or 7) and possibly even harmful to them. Dr. Healy also discusses how computers can be either beneficial or harmful for older children depending on how the computers are used. When used in a creative manner, technology can be a helpful tool to aid learning. When misused, it can dampen creativity, decrease intrinsic motivation and love of learning, and replace valuable "low-tech" learning experiences such as hands-on art or nature exploration.
It seems clear to me that rather than wasting resources on "one size fits all" technology, schools ought to invest money in individualizing instruction for each student so that he/she learns in the way that's best for him/her!