not easy, I have used shatter with the pieces set at the smallest possible, and mixed it with a bunch of other filters to aid in the illusion. But that only goes so far. Obviously, if you have mad skills and own maya, a true hi end particle system is the true way to go, but not all of us are there yet. I have a sample of letters blowing away that is sort of close to what your talking about, on my demo reel.
SuperNova
Animation & Visual Effects
Scott Novasic
Los Angeles Ca
web:https://web.mac.com/finaleffects