The results of ab initio molecular dynamics simulations of liquid water and liquid water-vapor interface using the Perdew-Wang 91 (PW91) exchange-correlation functional are presented. The structural and transport properties of liquid water are comparable to the previous results using Becke-Lee-Yang-Parr (BLYP) functional and experimental data. The shape and the position of the first peak in the oxygen-oxygen radial distribution function is in good agreement with the most recent neutron diffraction data. The ab initio molecular dynamics simulation of liquid water-vapor interface, which is the first of its kind, suggests a preferred orientation of the surface water dipole towards the bulk region.