  It was recently shown that unbroken N=1 Susy relates, in a model independent
way, the magnetic transitions between states of different spin within a given
charged massive supermultiplet. We verify explicitly these sum rules for a
vector multiplet in the case of massless and massive fermions. The purpose of
this analysis is to provide the ground for the broken susy case. We study the
modifications of these results when an explicit soft Susy breaking realized
through a universal mass for all scalars is present. As a by-product we provide
a computation of the $g-2$ of the $W$ boson in the standard model which
corrects previous evaluations in the literature.
