Dear Van, Congratulations on this lovely picture of your kids - I'm glad it did so well as it really does show trust and friendship. When I was voting I thought these kids were yours and told Jack, too. The expressions on their faces are wonderful. That new D70 is doing a great job for you - the bokeh in the background is perfect!
LOVE the hair light. Very well exposed with nice composition too. It would have been a little more powerful and "friend" oriented if the girl on the swing was laughing or looking at the girl behind her. The connection here is more between the younger girl and the photographer, not the girl behind her. Very nice photo though.
Some movement or out of focus on the bottom left. This might work well in black and white also because of the movement and contrast. Like the backlight and halo effect on there hair. Nice photograph The pose is excellent.