This definition entails many things, but for our purposes let us to mention only two:
-The perception is done by "paranormal" means, not by the usual or normal ones.
-The future information already exists, and it's only accesible by precognition.
But if it's true (i.e. the future information already exist), then how could free will to exist?
Suppose the future information is that Barak Obama will retire, by his own will, from politics in august of 2010. The person with precognition actually "see" Obama retiring, and all the specific details surrounding it (for example, the news on CNN, the hour of the event, etc.)
It seems to imply that all of these events are already determined in advance; they're simply unknown by normal people who lack precognition skills.
But metaphysically, the event in question (and all the related circunstances) will exist in advance. If it's true, then we could argue that free will is an illusion based on ignorance of the (already existing but not accesible by most people) future information.
My opinion is that the future information (e.g. Obama's retire in the example) actually doesn't exist as actual and determined reality. It only exists as a possibility, the probability of which is projected on the future by our minds.
Precognition would allow to grasp a probable causal chain (deriving from the current states of affairs) resulting in the event in question (e.g. Obama retiring), but the causal chain is not fully deterministic, because free will is not part of that chain and the will of the intervining persons (Obama) could freely change.
But, given that the will is influenced by many factors, and those factors could be anticipated or known (by normal and paranormal means), you could know (with some probability) that a certain event will happen.
For example, I can ancitipate that if the lakers win the NBA championship this year, the lakers fans will celebrate and be happy. It doens't mean that free will doesn't exist, only that given a known patterns of human behaviour, you can predict certain human behaviour under specific circunstances.
If it's correct, precognotion would be only a more sophisticated and refined skill to predict, based on known patterns (known both via normal senses and paranormal perception) what's likely to occur in the future.
But the future as such doesn't exist in the metaphysical sense apparently required by the concept of precognition.