Not big on letting my boy game even with the wii.
I was an avid FPS player for many years and helped run a gaming clan and find them to be a blackhole for productivity and life. I think I let my son play his wii like once every 2 weeks. If he is bored we shot pucks or play catch.
Be careful about online play. I have heard some very creative conversation on gaming servers.
and have heard 10 year old kids go on fbomb rants and worse.