We have times designated for "fun" learning, like educational computer games or chess. Within those times, they can choose what they like to do. I have computer folders titled "DS8 in the morning" and "DS5 in the morning" for them to open so that the sites they visit have been pre-approved by me.
Outside of those free-choice times, computer use is limited to specific schoolwork. (We use Plato/Cybered science and Rosetta Stone for foreign language.)
But these limits are in place because I see a negative effect on their behavior if my kids spend too much time using the computer. If you see good stuff coming out of computer time, then I'd say it's just as valid a method as any other educational tool. Use what works!
