Honestly, I see very little difference between the "normal" locks that cost nearly $40 and the cheap one that I got on ebay for $2. I used it extensively in the dorms and had no problems with it jamming. It has a 5 foot cord, roughly, and is a 4-digit combination. There is also one available that is a 3-digit that has a retractable cable, although I feel that that one could be more easily broken.
The point is though, if some one wants your laptop, not even a $200 cable will keep them from getting it. That cable is just enough to keep the amateur criminals at bay for a while.