Animated snow

I’ve done some 3d modelling with blender before. Though animation is one of the parts that I’m most unfamiliar. I’m doing a short clip where I should have animated snow. I could add the snow with my video editor, but for realism the best result would come with blender.

Whats the easiest way to create falling snow to be rendered with the actual animation?

And I would prefer step by step tips :yes:

Thanks already for all of you!

These links might help:
http://blenderartists.org/forum/archive/index.php/t-175.html
http://www-users.cs.umn.edu/~mein/blender/tutorials/dust/