How many planets of the Solar System have water on their surface?

Only Earth has surface liquid water. At least, that is as much as we know thus far.

Some of the moons of Saturn and Jupiter have liquid water in their interiors...but their surfaces are frozen.

Just about all planets have ice of some flavor. Water ice is just about on all planets too...except very rare on Venus (if it even exists there at all). You wouldn't expect it to be on Mercury, but it indeed does, in permanent shadowed zones as MESSENGER's new data has revealed to us. The Moon also has ice in permanent shadowed zones.

Mars certainly has ice. Primarily carbon dioxide ice, but it has some water ice as well. Clouds on Mars are entirely ice, and they never produce rain, mostly hail.

Jupiter/Saturn/Uranus/Neptune are filled with clouds. All those interesting patterns on them...those are clouds. Not necessarily the same flavor as Earth clouds though.

The rings of Jupiter/Saturn/Uranus/Neptune are rocks and ices.

Uranus and Neptune have icy interiors.