We consider the low-energy dynamics of a pair of distinct fundamental
monopoles that arise in the N=4 supersymmetric SU(3) Yang-Mills theory
broken to U(1)รU(1). Both the long distance interactions and the short
distance behavior indicate that the moduli space is R3ร(R1รM0โ)/Z where M0โ is the smooth Taub-NUT manifold, and we confirm
this rigorously. By examining harmonic forms on the moduli space, we find a
threshold bound state of two monopoles with a tower of BPS dyonic states built
on it, as required by Montonen-Olive duality. We also present a conjecture for
the metric of the moduli space for any number of distinct fundamental monopoles
for an arbitrary gauge group.Comment: LaTeX, 11 pages (a reference is added, the mass-dependence of the
moduli space is clarified and corrected.