Heh, thanks. I thought that sounded familiar :)
So about the critical empowered spell. Normally, the spell would inflict a d6+3 strength penalty.
Empowered that would be (d6+3) x 1.5
Critical'ed, that would be 2d6+6
My guess is that both operate on the base 'damage', so you'd get (d6+3)x1.5...