The total atomization energies and equilibrium dipole moments of some small first-row polyatomic molecules are calculated at the Ornstein-Uhlenbeck diffusion quantum Monte Carlo with the floating spherical Gaussians. By using explicitly correlated wave functions built from the spherical Gaussian-type orbitals and geminals to be the trial wave function, this work gives accuracy that is comparable to or better than previously theoretical estimates. The accuracies are less than 0.6 kcal mol(-1) and 0.007 D for total atomization energies and equilibrium dipole moments, respectively. We also compare the performance of three different approximations in estimating expectation values of equilibrium dipole moment. (C) 2003 American Institute of Physics.