  We investigate the predictive power of Collins, Soper, and Sterman's
$b$-space QCD resummation formalism for transverse momentum ($Q_T$)
distributions of heavy boson production in hadronic collisions. We show that
the predictive power of the resummation formalism has a strong dependence on
the collision energy $\sqrt{S}$ in addition to its well-known $Q^2$ dependence,
and the $\sqrt{S}$ dependence improves the predictive power at collider
energies. We demonstrate that at Tevatron and the LHC energies, the $Q_T$
distributions derived from $b$-space resummation are not sensitive to the
nonperturbative input at large $b$, and give good descriptions of the $Q_T$
distributions of heavy boson production at all transverse momenta $Q_T \leq Q$.
