A good resource to check out the schools is http://www.schooldigger.com.
Gwinnett County School website: http://www.gwinnett.k12.ga.us
Forsyth County School website: http://www.forsyth.k12.ga.us
Keller Williams Realty Atlanta Partners
When it comes to the "best" schools..., well that is a determination which should be made on a personal basis. You may find that a particular school has a special program geared toward a type of need your student could benefit from.
My client who have bought homes in these schools districts are extremely happy, not only with the schools also with their homes rapid appreciation which is highly supported due to the strength of the schools.
Here I have provided a few links to reseach;
Another great resource is the site listed below. This site has personal experiences and evaluations. My clients find it's a fantastic resource.
Robin Lanese, REALTOR, ABR, CRC, REoS
Atlanta Housing Source Team
Solid Source Realty, Inc