Have you seen Healthy Sleep Habits, Happy Child by Dr. Marc Weissbluth? It's a great book and it helped us help our twins to become great nappers and sleep through the night.
As one white rose said, you need to establish a night time routine: dinner followed by a bath, a nice rub down with lotion, clean pjs, and quiet time with the family. Then a few minutes before bed, let him know that's what's going to happen. With our twins at 7 we say "ok, time to brush your teeth and get in bed". We brush teeth and then they get into their cribs and I read to them. Then I give hugs and kisses, put their white noise on, turn out the lights and close the door.
Consistency is key. Whatever you decide for your night time routine stick with it.
at 7:53 PM on Dec. 15, 2008