Fishing a dry-dropper rig can be one of the best (and fun) ways to fly fish. You are covering both of the most effective fly fishing methods at the same time - dry fly fishing and nymphing. The Dry-Dropper Rig selection includes dry flies that float well and can hold up the nymphs in this group. Check out the pictures on how the rig should look and for a good design of a typical dry-dropper leader.
TIP: Use the bigger, foam dry flies with the larger nymphs; the smaller dry flies with the smaller non-bead head nymphs. Don't forget to put floatant on you dry fly...