use particle systems II
mess around with the birth death size
birth= .02
death= .001
use directional system
keyframe the birthrate with HOLD keyframes
so that , for example, at 1 second the keyframe for birthrate is 20 and then 10 frames later another keyframe that is "0".
then mess with the longevity and the air resistance
don't go very high with the air resistance, like .2, .3
then precomp the effect layer and apply Force motion blur to the layer, and add GLOW, now you've got something to work with
goog luck.