I keep posting the same reply, forgive me. BUT, I highly recommed the video series on encouraging good behavior/managing difficult behavior in your children. You can buy it, or borrow it from some libraries and school districts. I was sceptical, but got the exact results, that the video said I would!!!
Please, check out the tape(s)called;
1-2-3 Magic by Dr. Thomas W. Phelan

I have 4 BOYS, ages 6, 4, 2, and 11 months. My oldest is very active, dominant, and strong willed. My husband and I use this SPANK-FREE method, AND IT WORKS PERFECTLY!!! Please let me know if this is helpful to you!