cubano,
In the Classical sense of causality you're correct. But there are space-time topologies that don't preclude the appearance of effect preceding cause.
Take the topology of a closed timelike curve (CTC)...a circle if you will. You can have a series of events along the circle that would appear to occur in the order Effect -> Cause. But if time is looped into a circle that is not especially a problem because it is self-consistent. On the first time through the loop "effect" comes first followed by "cause". But on the second loop, because "cause" already appears the traveler next encounters "effect".
This description is actually one of the topologies of cosmology that is being studied relative to the Big Bang event. If the universe begins, not as a singularity, but as a CTC then in a self-consistent manner you don't have to ask the question, "What event caused the Big Bang if there was no space-time before the Big Bang?"
This doesn't mean, though, that time travel to the past is something that is easily accomplished. That topology required the mass-energy of the entire universe. Most real theories that propose time travel to the past also require mass on the order of dozens to billions of stars...and then only allow at most a few years of travel. Even then, the theories have huge problems to overcome to make them workable.
But that's why we have people like Rainman. Physicists propose theories. Engineers are left to work out the "little" details.
BTW: There is a more practicle way of looking at the Cause-Effect ordering problem that has been experimentally verified.
Take the case of a distant star where some event occurs that leaves physical evidence of cause-effect in the stream of photons emitted by the event.
Normally we, here on Earth, would see the event played out in the "correct" order. But what if there is a large black hole between the star and Earth and the photon stream passes by both sides of the black hole on its way to Earth?
You have a gravitational lense in this case. Photons react to gravity - their path is bent by the gravitational field. Because this occurs we could see, here on Earth, the photons of the effect arriving before the photons of the cause because the effect ended up taking a shorter path through space-time to arrive here.
