As others have said Realflow is great for this, and even though it looks complicated what you are trying to do is extremely simple.

Further to that try and find someone selling an old copy of 3D World magazing, it had a free version of Realflow on it, it was limited to 50,000 particles but thats more than enough for what you need.

Jon

DA Portfolio - http://jonj1611.daportfolio.com/