Wouldnt like my child to be sat infront of a computer on a reqular basis until 12 or so. Hand held stuff is ok in moderation, i think they need as much real life interaction as possible.
Its worked very will with my step son and will work well with my new son. It also worked well with me.
Obviously people will not agree with me because this is a computer overclockers forum, but its very much like young people taking drugs - they think its ok because everyone does it or has done it and its not till later in life when they realise they were wrong and everyone doesnt do it, unfortunatally some people dont grow up and they continue to think everyone does it.
EDIT : Now i think about it my family always had a computer from BBC to Archimedes and PC but i was too busy doing things outside to spend much time on them.
Im not having a go at the OP, i dont know his situation what so ever. I just find it odd that children as young as that and younger are allowed to spend huge amounts of time on computers.
Computer games were not as addictive as they are today (probably due to massive loading times!) and there were no ratrings to worry about, ive seen first hand what a mmo can do to an inoccent child, its not pretty.
But for the OP i would definatally explore the cbeebies website.