  Recent experiments on the amorphous magnetic semiconductor Gd_x Si_{1-x},
Phys. Rev. Lett. 77, 4652 (1996), ibid 83, 2266 (1999), ibid 84, 5411 (2000),
ibid 85, 848 (2000), have revealed an insulator-metal transition (i-m-t), as a
function of doping and magnetic field, a spin glass state at low temperature,
and colossal magnetoresistance close to the i-m-t. There are also signatures of
strong electron-electron interaction close to the i-m-t. Motivated by these
results we examine the role of doped magnetic moments in a strongly disordered
electron system. In this paper we study a model of electrons coupled to
structural disorder and (classical) magnetic moments, through an essentially
exact combination of spin Monte Carlo and fermion exact diagonalisation. Our
preliminary results, ignoring electron-electron interactions, highlights the
interplay of structural and magnetic `disorder' which is primarily responsible
for the observed features in magnetism and transport.
