We actually just bent this year - well I guess last year - as last Christmas we got the kids DS. The thought was as one child attends the others sports events, they have something to bring and keep them quiet or on a long car ride.
This year we got the WII - as it has only been a little over a week, we are just starting rules. For example, homework/studying/reading first. Almost can use it as reward. I also during the week after Christmas told them they had to go outside and play. I guess you just use your common sense if it seems to get out of hand.