Let's learn a lesson from a fish.
I have a beta fish (back in UCLA) in the care of one of my friends (thanks). I love that fish and his name is Ninja. The above picture is not Ninja, but close enough (Ninja is definitely more good looking). He has lots of fun hobbies and he loves practicing his free will. He chases after little bugs/gnats that happen to get into my room (its awesome to watch). He makes bubble nests with lots and lots of bubbles (sign of happiness... and wanting to mate). He takes rests at the bottom on the rocks and swims between whatever he wishes. He also watches me study and encourages me as I work late into the night. With all that said - Ninja has 100% free will, HOWEVER he is CONFINED to his TANK as a FISH. He does whatever he wishes, but whatever he wishes to do is restricted by the fact that he is a fish. This means he needs water to stay alive, and he needs to stay in his tank. He cannot free will himself to be human, or free will himself to be a dog, or free will himself to fly, but he has free will.
Thus it is with humans. We have free will but we are bounded by the fact that we are humans. We cannot free will ourselves to be God or to fly ourselves out to space (without spaceships). But you can drop a pencil right now if you want or write a blog entry (like me) if you want right now. However, you definitely cannot free will yourself to salvation. You cannot free will yourself to believe. Here's WHY.
Humans in our NATURAL state of free will would NEVER choose God. Psalm 14:2-3, Romans 3:10-12. God looks down from heaven to see if there are any who seek God, there is none - no not one. We know that in our free will bounded by the fact that we are human we would never ever choose God. John 6:44, John 6:65. As a Christian, I am so glad that this be true because I know I would have never chosen God - I would love to rebel as that is my nature. Then the beauty of God's grace is that He pierces through that boundary and gives us grace and draws us to Him that we may believe. YET, it is not that God FORCES us to believe. Far be it from that. He as God draws us and wills us to believe through His grace and majestic wonder.
Thomas Watson in All Things for Good puts it this way:
"It is a sweet call. God so calls as He allures; He does not force, but draw. The freedom of will is not taken away, but the stubbornness of it is conquered. 'Thy people shall be willing in the day of thy power' (Psalm 110:3). After this call there are no more disputes, the soul readily obeys God's call: as when Christ called Zachaeus, he joyfully welcomed Him into his heart and house."
And this... is my attempt to explain how free will exists with predestination =] Thank you Ninja for the help.