Children's low cost laptop fund data

General Questions

What evidence is there that providing every child with a laptop is beneficial?
What benefit do the children derive from owning/having one?
Won't the laptops get broken a lot?
Can we really get laptops that will be useful and fully functional for under $400?
- In addition to the price of the laptop, what are the other costs?
How are the teachers going to learn how to use this new tool?
What infrastructure is required to support every child having a laptop?
How will purchasing laptops help increase student test scores?

Why Linux?
What specific infrastructure does the XO need?
Won't the XO get broken a lot?
How will teachers learn the XO?
What other costs(non infrastructure and not included with the original hardware costs) should we expect?