I am relatively new to the world of photography but being that I am going back to school (do to being laid off) for communication art and design I have really become a fan of photography. I recently purchased a Nikon D90 and I love taking sports photos of my 3 nephews. Right now is football season and I really would like to be able to get some good pictures at one of their night games. I unfortunately do not have the funds to get a low f stop lens so I am limited to the Nikkor lenses I got when I purchased the camera. My question is what would be a good setting to get the sharpest pictures without blur in a pretty bad lighting situation for night football. I did purchase the SB-600 AF Speedlight external flash but I have seen mixed reports on wether to use a flash or not. So if anyone has any input I would be greatly appreciative.