I was as skinny as they came. But you have to realize that in order to bulk up you have to eat. Alot. Like more than you have ever eaten before.
I tried the creatine, whey protein, etc. on my old workout routine, and the results were mediocre at best.
However, since I started eating more protein, and taking in alot more calories, my weight has gone up 5 lbs. in the last month. Which is completely unprecendented for me. I ran out of protein supplement, so I am going to start that again. But really, eating makes all the difference.