S.C.
Hi K.,
We got an extra 6 months in the crib by using a crib tent. These are wonderful and can be purchased at the Babies R Us or online (~60.00). Our son was a climber too, and no amount of "stay in your bed" helped that. When we finally moved him to the toddler bed it was such a short time that we wondered why we hadn't gone directly to a twin bed with rails. We put the twin on the ground (boxspring and mattress) at first so that it did not seem to high. After he got his "big boy" bed, we have had no trouble with him staying in it. We made a big deal about how he had grown and how he was being given a new bed and new responsibilities. It worked!
As for doorknob covers: my husband and I disagree. I think they are a form of restraint which can go awry should the child need to leave the room (think: emergencies or simply potty training), and he thinks of them as a form of security for the child. In the end, our boy just circumvented them by dismantling them so they were useless anyway.
I really believe the real key is communicating with the child about things that are harmful (when they are old enough to understand~24months) and to toddler proof the house. It is imperative to do this. Once they start to feel independent they can put themselves in much danger. I also agree that moving the computers is very important. Space is always tight and I know that having away space for the computer is ideal, however this is your child's room and he must be able to be secure and safe and comfortable in it. As he grows, there will be less need to keep things so secure, but until that time, if you can it would really benefit your son to move the computers.
Best of luck with this!
S.