Almost every feature of the particle system can be configured, including:
Background image and ground
Particle batch size, to determine what the best number of particles to render in one batch is
Particle emit rate
Particle spawn position
Particle blend mode
There's not much to say. Its a GUI application, and you can tinker with the controls. Most of them should be pretty self explanatory.
Hold the left mouse button and drag to look around, and use the cursor keys to move. The Enter key toggles fullscreen, and Escape exits.
Windows 2000/XP (May work on Win9x)
GeForce 2 or greater graphics card
A CPU of some description