Alanbikehouston has good advice. The conventional wisdom from what people do where I live (other than not riding a bike around college campuses that is too valuable if its stolen) is to use a a high security U-lock, and a good cable lock. If its not too much weight, pairing a New York Lock from Kryptonite up with a Rottweiler series cable lock from Onguard locks will for the most part ensure your bike remains where it is.