5x5 is just 5 sets of 5 reps of calculated weight for each set. Each set gets heavier and you add minimum 10 pounds to the exercises per week. The 5th set should be 5 reps of the heaviest weight you can do and fail on the finish of the 5th rep. I was getting to where I would plateau with my exercises, found this Bodybuilding.com - What Is The Best 5x5 Workout That Will Produce Amazing Muscle Gain? and have seen great gains and results in my first month. The first 12 week program on that page is what im doing.
I'll have to give it a try. I do drop sets and they seem to work well for me.