In an earlier thread (Billiard Ball Physics), I posted some equations and stuff for collisions. Those equations that I posted were if one ball was stationary. I couldn't quite remember the equations if both of the balls were moving. So, I guess this is just kind of a little tidbit of information for you guys, but here are the updated equations.
v1i = object 1's initial velocity v1f = final velocity
v2i = object 2's initial velocity v2f = final velocity
m1 = mass of object 1 m2 = mass of object 2

v1f = [(m1 - m2)/(m1 + m2)]*v1i + [(2*m2)/(m1 + m2)]*v2i
v2f = [(2*m1)/(m1 + m2)]*v1i + [(m2 - m1)/(m1 + m2)]*v2i

Now using those equations, you can find the final velocities if both balls are moving. Looking back at the earlier post, you can find out how to determind bounce angles and other things like that.

Hope these prove useful.