We present ADHM-Nahm data for instantons on the Taub-NUT
space and encode these data in terms of Bow Diagrams. We study
the moduli spaces of the instantons and present these spaces as finite
hyperkaehler quotients. As an example, we find an explicit expression
for the metric on the moduli space of one S U (2) instanton.
We motivate our construction by identifying a corresponding string theory brane configuration. By following string theory dualities we are led to supersymmetric gauge theories with impurities.