Man is endowed with a free will that is the same before or after regeneration. It will be the same free will that he carries with him to heaven or hell. That will is not violated. The will however, is like an engine. The input, or the fuel, is man's heart. The output is man's actions and deeds. It is not the will that is changed, but the heart. Same engine, but different inputs— which then results in different outputs.I will give you a new heart and put a new spirit in you; I will remove from you your heart of stone and give you a heart of flesh. (Ezek. 36.26).
Although I don't call myself a Calvinist like Heddle does, I like this analogy of the will as the engine while the heart is made new. So true, God does not clean up our dirty heart, He gives us a new one!