I have just read some earlier posts and people were saying that the accretion disc model does not explain prograde rotation, which in my mind it does (this one one of the few mainstream models I believe does make some sense)...
As I understand it, the accretion disc initially forms into bands of matter surrounding the star, so when a protoplanet forms in one of them it accretes most of it's material from ahead and behind it in it's orbit rather than from further in/away from the sun. In doing so, the material ahead of the protoplanet gets slowed down in it's orbit and hence falls slightly towards the sun, getting pulled in around the inner side of the protoplanet. The matter pulled in from behind gets sped up in it's orbit so it flies away from the sun and gets pulled in around the outside. The result would be prograde rotation.
The speed of a planet's rotation is generally proportional to it's mass, or at least to the mass it initially had before it's further growth from accretion of interstellar matter/solar wind particles. I am sure Jupiter has the fastest spin because it is the most massive planet. Saturn comes second in both regards. Neptune has the third fastest rotation and probably had the third largest mass on initial formation. I reckon it was subsequently overtaken in size/mass by Uranus which grows faster due to having a stronger magnetic field (funnels solar wind ions in at the poles) and maybe because it's closer to the sun. [oh, and before anyone tells me Neptune is the 3rd most massive planet anyway you might wanna read this]

Venus's lack of rotational momentum must be due to tidal forces (or maybe it's Velikovsky-style travels around the solar system
