I managed to come up with an Ellipsoid vs Ellipsoid intersection test that seems to work perfectly. But when one of the ellipsoids has the same radius on all axis (ie. a sphere) it doesn't work correctly. Is a sphere not just an ellipsoid like I described? The effect I get is like testing a sphere against 2 other spheres one on top of the other, kinda like a figure 8. I have the same problem with Cylinders. My Cylinder/Sphere test works fine, but I'm not sure how to transform the cylinder into ellipsoid space. Any pointers would be appreciated..

function ellipsoidVellipsoid(pos1, pos2: TAffinevector; r1, r2: TAffinevector): single;
var
    dir: TAffinevector;
    ar1, ar2: single;
begin
    pos1 := vectordivide(pos1, r1);
    pos2 := vectordivide(pos2, r1);
    r2 := vectordivide(r2, r1);
    r1 := affinevectormake(1, 1, 1);

    dir := vectornormalize(vectorsubtract(pos2, pos1));
    ar1 := Sqrt(sqr(r1[0] * dir[0]) +
        sqr(r1[1] * dir[1]) +
        sqr(r1[2] * dir[2]));
    ar2 := Sqrt(sqr(r2[0] * dir[0]) +
        sqr(r2[1] * dir[1]) +
        sqr(r2[2] * dir[2]));

    result := SphereVSphere(pos1, pos2, ar1, ar2);
end;

Oops, wrong forum. Feel free to reply just the same. :)