The computer is just a tool. I'd think it has no direct effect on education whatsoever. Smart kids with supportive parents will gain a great deal from having a computer. Dumb kids with dumber parents will spend hours on Youtube, twitter etc and learn nothing of consequence.
Exactly. If the parents are buying the computer as a teacher in the same sense that they bought the TV as a babysitter then they're doing it wrong. Kids who want to learn and grow will see it as a tool to help them perform that task, whereas kids who want to play Farmville and watch YouTube will see it as a tool to help them perform _that_ task. Perhaps the presence of the computer in the home strengthens the divide, but the divide has already been there. The student has to want to learn. There are exceptions, but generally (at least in American culture) low-income households and neighborhoods don't place a very high social value on education, and kids pick up on that at a much earlier age than a home PC can affect.