Driver position whats right?

[Robert O' Keeffe]

I am messing around with driver head position,and would appreciate any comments on head position. I normally setup with the head flush to ball, but have been told that ideally it should about 4" away from the ball. I do find that with the latter position, it encourages a straighter ball flight. Is there any hard and fast rule on this issue/

Regards,
Robert