Alan,

Thanks for the help, but you seem to have left something out because it doesn't work the way I tried it.

"6.instance the small plane onto the particles."
this doesn't make sense because now my little objects are falling from the sky when they shouldn't appear until the hit the collision object. Shouldn't there be a collision event to kill the particles falling from the sky and spawn a new one?

To more easily view the normals, what I did was I instanced cones instead of planes. When they hit the collision object, they flip 180 degrees and then they slowly slide down the slope rather than staying put where they are.

I've attached my test file so you can see if I implemented your code incorrectly.

Thanks,
-dann