Ok, my math just isn't so great (I think I'm gonna go buy a book)...

I'm trying to generate x number of random points, all within a sphere. Big problem though, I can't seem to figure out the math. :?

I know the radius of the sphere, and it's origin (let's just say it's 0,0,0 for simplicity's sake). I've tried several methods, but I always end up with the points being distributed too far within the sphere, or going outside of it. Anyone know the math for this? It would be greatly appreciated.