We are studying a variety of semileptonic decays of heavy-light mesons in an
effort to improve the determination of the heavy-quark Standard-Model CKM
matrix elements. Our fermion action is a novel, improved ``fat'' clover action
that promises to reduce problems with exceptional configurations. Dynamical sea
quarks are included in a mixed approach, i.e. we use staggered sea quarks and
fat-clover valence quarks. Here we report preliminary results.Comment: LATTICE99(heavyqk) - 3p, 4 Postscript fig
