You can find this awesome tool at http://anydice.com/.
In the command box at the top you can enter either a single command, or multiple ones to compare the results directly. Each output command goes on a separate line.
|output 2d10||Shows the probabilities for non-exploding 2d10|
|output 2d [explode d10]||Shows the probabilities for exploding 2d10|
|output [highest 2 of 3d [explode d10]]||Keeps the highest 2 on exploding 3d10|
Check out the odds of 19!
It's a pretty slick tool and great for quickly determining odds of complex dice probabilities - an important consideration in any game design activity. The functionality goes quite a bit further than what I've illustrated here, including a couple of different ways of graphing the rolls, the odds of getting at least or not more than a certain number, and more functions.
I've previously donated to this site - if you make good use of it, consider doing the same. I support quality work!