  We report on the gauged supergravity analysis of Type IIB vacua on K3x T2/Z2
orientifold in the presence of D3-D7-branes and fluxes. We discuss
supersymmetric critical points correspond to Minkowski vacua and the related
fixing of moduli, finding agreement with previous analysis. An important role
is played by the choice of the symplectic holomorphic sections of special
geometry which enter the computation of the scalar potential. The related
period matrix N is explicitly given. The relation between the special geometry
and the Born--Infeld action for the brane moduli is elucidated.
