join date march 2005. i am guessing you are pretty new here. almost any training routine will work. that said I like any program where you train anything more than once per week and has proggressive overload and denconditioning.
HST, madcows 5x5, or west side all are pretty good IMO.
however, as booey said, gaining weight is all about a lot of protein, good carbs (oats, brown rice, whole wheat bread, green veggies, etc), and healthy fats (peanuts, almonds, flax oil, fish oil, etc).