My personal opinion is to avoid the computer unless there is some specific need it can fill. Such as the mamas with deployed partners and kids are watching vids of dad. I think kids at this age are much better off being active participants in things. I think there is a continum from passive to active going TV - Computer - Regular Life.
I am considering the computer as an option for my dd, but only because she was just diagnosed with Juvenile Dermatomyositis and will have to sit for IV infusions three times a week. However I will try books and seated pretend play first, then art projects, then workbook type stuff and lastly the computer.
Actually I'm more of an unschooler and would tend to stay away from the workbooks too under normal circumstances, but if it's something that will engage her mind and keep her from feeling depressed then it is of course the much lesser of two evils. Same thing with the computer, though I am keeping starfall and selected you tube videos in my back pocket if needed.