Good job on take charge and believing you can make a serious difference, that is part of the job already doneAs for your routine I don't intend to come off as an ass but going by what you are saying this "arnold workout" seems to be tweaked for folks who are at an intermediate/advanced stage (which is probably why your massive friends are doing it). For beginners a whole body workout seems to work better judging by what the other skinny folks (including myself) are doing on this forumDo go through the stickies on full body routines which utilize mostly compound exercises - heavy lifts at the lower end of the rep range on a specific set of exercises with the variable being the weight lifted, while the number of sets and reps remain constant. If your current routine does not have you doing squats, press, bench, deadlift, rows then it might make sense to have a relookI can myself vouch for SS, it's packed on approx 25lbs on a skinny guy like me in 5 months. And you have a lot of folks who've done far better than me when it comes to BW and muscle mass improvement in a 5-6 months spanDo check - Starting strength, all pro's beginners routine, stronglifts routines. They've been proven to work best for most beginners