In general, I believe that one must put the topic of computers into a larger context. How much does the child get to play outside? Does s/he watch tv and videos? Is s/he in a busy frantic city or in a sleepy rural setting? How healthy are general family rhythms? And, most importantly, how does the child react to the computer?
So here are some thoughts, based on what we did as a family....
* No computer at all before 10. Not even in play, not even on Mama's lap. This is an adult tool, not for young children. Treat it as you would a power tool such as a lawn mower or electric saw.
* At 10 or 11 you could get a mild computer game for your child and/or perhaps look at web sites together. Computer time not to exceed an hour a week and no use of the internet except with an adult.
* By 12, 3 hours a week of games and some time looking up specific things on the internet with you in the same room.
* By 14, 3 - 4 hours of games per week and use of typing facilities, Wikipedia and internet as needed - but no internet access on her computer. She must use yours for internet access and ask first, so you are aware of what she is doing.
*By 16 unrestricted use of the computer. She should be able to use it sensibly by now. If she wants to use chat rooms, now is the time - not before.
These kinds of rules will prove almost impossible for some people - especially if your child's social contacts seem based on computers and such. There is no easy solution to this - but you can always have strong and clear rules in your home. One thing I would certainly prohibit is any kind of handheld or virtual reality type of games run off the computer or television. I would also not allow any access to chat room until late teen years. I also do not recommend unrestricted use of the internet without a parent present until the teen is about 16.
And running through all this is the warning - observe your child! It could be that she has a healthy take it or leave it attitude toward computer use - if this is the case you are blessed and it is unlikely that use of this machine will be any big deal. BUT - such children are rare in my experience. Most get sucked in one way or another. Serious red flags should be waving for you if your child's behavior is at all effected by being on the computer. If he is listless (and yes, I said he on purpose there - this seems to effect boys more than girls), restless, out of himself, twitchy or bad tempered after using the computer - if limiting computer use results in furious rampages and tempers or tears - then you have an addictive situation on your hands and cold turkey (ie no computer at all ) might be the only solution. I am not exaggerating. Addiction has to do, for the most part, with stimulation - and the stimulation of the computer can be as powerfully negative and unhealthy for your child as if he sat down and ate a 5 pound bag of sugar or other addictive substances. In the end, the issue is about health. And, I would say categorically, that use of computers by children in no way optimizes their health. It might not be too bad - that is how my husband and I have felt about its use by our age 10+ sons - but it certainly does nothing to enhance their health. And, our sons lived on a farm with no TV and maximum once a week video until they were 13.