Dear Greg, I have learned to read and write with 0GB, actually with no PC at all. :~D
This is only one more thing that blocks communication between human and human. (teacher and child).
These guys born in the 80's are lonely enough. I know there is life on the net, but there is a saying, that people, who doesn't got touched or talked to for a while, will easily misunderstand any kind of input.
I personally don't recommend pc for kids other than data mining (eg. wikipedia). Actually boys at my age spend all their time after work with the PC (not going out at all, nor chatting, nor doing anything together). That's embarrassing in a relationship.
Look at this: you go home, your wife's chatting on a chatsite, your kid's playing something, none realizes that you arrived, and it can turn to a habit in your family. They don't even realize if you don't go home.