Chris,
My son started on an XR-100 when he was 9. At 12 years old he was ready for a bigger/more advanced bike. He would only get one summer out of an 80/85, and a 125 would be too big. I read lots of reveiws and settled on the KX-100. I was looking for something that would grow with him. The bikes power and suspension are great.
The power is smooth, with good low end for the beginning 2-stroke rider. As your daughters skill increases, she just needs to twist the throttle for more power. The little bike can scream.
The suspension is great too. My son can take every jump I do on my RM-250.
Depending on how big she gets (height) the bike could last her for years to come. I've read that most women in the 5'2"-5'8" range really like the bike for it's ergonomics, light weight and smooth power delivery. My son's 2003 only weighs 150 pounds.
I think you (your daughter) would be happy with the KX-100.
Hope this helps, Steve.