This paper gives a generalization of some results on Hilbert schemes of points on surfaces. Let $M^G(r, n)$ (resp.~$M^U(r, n)$) be the Gieseker (resp. Uhlenbeck) compactification of the moduli spaces of stable bundles on a smooth projective surface. We show that, for surfaces satisfying some technical condition: \begin{enumerate} \item[(a)] The natural map $M^G(r, n) \to M^U(r, n)$ generalizing the Hilbert-Chow morphism from the Hilbert scheme of n points on S to the n-th symmetric power, is strictly semi-small in the sense of Goresky-MacPherson with respect to some stratification. \item[(b)] Let $P_t (X)$ be the Intersection Homology Poincare polynomial of X. Generalizing the computation due to Gottsche and Sorgel we prove that the ratio $\frac{\sum_n q^n P_t (M^G(r, n))}{\sum_n q^n P_t (M^U(r, n))}$ is a character of a certain Heisenberg-type algebra. \item[(c)] Generalizing results of Nakajima we show how to obtain the action of the Heisenberg algebra on the cohomology using correspondences. \end{enumerate}