The short answer, sparko, is that there are two theories re: ball placement.
Theory one is to play the ball in a constant spot, and move your feet (adjust your stance) wider and narrower for longer and shorter
clubs, respectively.
Theory two is to keep your stance the same, and move the ball, with Driver being played inside your lead heel, and wedges being played between your heels.
I prefer method two, and always 'cheat' the ball closer to middle.
I, too, sliced my driver, but was playing the ball off my lead TOE, not heel.
The slicing stopped once I brought the ball to inside my heel.