S.W.
Of course he's going to get out of bed now, that is the fun of it, isn't it? I'll bet once he is used to his new situation then he'll go back to his normal sleeping. At that age, my son slept about 11 hours at night and took a 2 hour nap.
I would ditch the crib all together and get him a regular twin sized bed. Cribs are hardly comfy and cozy and rather small anyway so I would skip it as well as skip a toddler bed. We got my son a Little Tykes race car bed which we loved. My son loved the novelty of sleeping in a car and I loved it because the sides were slightly higher so he didn't fall out. We also got him some cool sports bedding that he helped pick out. After you put him to bed, I would just hang outside his room and when he gets up the first time, explain it is bedtime etc, then everytime after the first time he gets up, with no talking, put him straight back in bed. It is exhausting but after awhile he'll stop trying.
I also like the first persons idea of rewarding him for staying in bed, rewards work great for stuff like this. I would definately avoid laying down with him or you are going to make it a habit and be doing it for years to come.
With my son, who actually didn't get out of bed for some reason, I think he was afraid to, I took his ocean wonders aquarium and taped it to the side of his bed so he could still listen to the music he was used to. He was 2 1/2 when we first introduced our son to his new bed. So, music may be a good idea to help. Good luck :)