C.P.
M.,
I just went through all of this over the summer with our then 16 month old son. He climbed over/fell out of his crib and thankfully wasn't hurt. But we decided not to wait until he did get seriously injured and moved him into a junior size bed (bigger than a toddler bed but smaller than a twin).
The transition took about 6 weeks or so. First we bought a nice gate with a door for his room. That is a must. You basically turn the entire room into a crib. Then for the first few weeks we went back to rocking him to sleep and then putting him to bed in the crib so that he'd have time to get used to it. After 2 weeks, we started taking him to bed awake and staying in the room until he fell asleep. After 2 weeks of that, we just went cold turkey and put him in bed, read books... creating a nice bedtime ruitine for him... and then we'd turn his music on and shut out the light and leave the room. Of course, for probably 3 to 4 nights he cried hysterically at the gate. we use the Ferber method... so we would wait 5 minutes and then put him back in bed...wait 10 minutes and put him back in bed, wait 15 minutes.... eventually he would climb into bed and go to sleep. After a week or so, this whole crying thing was totally minimized. He got used to the bed pretty easily considering he was so little, and it's worked out really well.
good luck!