  By a result of Klyachko the Euler characteristic of moduli spaces of stable
bundles of rank two on the projective plane is determined. Using similar
methods we extend this result to bundles of rank three. The fixed point
components correspond to moduli spaces of the subspace quiver. Moreover, the
stability condition is given by a certain system of linear inequalities so that
the generating function of the Euler characteristic can be determined
explicitly.
