The first lock that you put on your bike, regardless of how cheesy, is about 90% effective because it forces the potential thief to use some kind of a tool. Using two dissimilar locks is even better because it forces the thief to bring two different tools. Thieves are lazy so they'll usually look around for an easier target. That's the good news.

The bad news is that to go from 90% to 100% effective is a high tech game of one-up-manship that you will always lose. Given enough time and technology, any safety measure that you can dream up, a thief will figure a way around. If you lock up your bike in the same place every day, and the thief really wants it, it's toast. The thief can figure out what he needs to bring with him to steal either the whole bike or whatever he wants to take off of it, pick his time, and do the deed.