  We study an exactly marginal deformation of N=4 SUSY Yang-Mills with gauge
group U(N) using field theory and string theory methods. The classical theory
has a Higgs branch for rational values of the deformation parameter. We argue
that the quantum theory also has an S-dual confining branch which cannot be
seen classically. The low-energy effective theory on these branches is a
six-dimensional non-commutative gauge theory with sixteen supercharges.
Confinement of magnetic and electric charges, on the Higgs and confining
branches respectively, occurs due to the formation of BPS-saturated strings in
the low energy theory. The results also suggest a new way of deconstructing
Little String Theory as a large-N limit of a confining gauge theory in four
dimensions.
