Mouse position and shoot...how?

Hello guys!
Please, can some one help me...?
I want to shoot a projectile in the direction of mouse position.
I want that the player can shoot anyware.
Here is the code...

function Shoot(){

ray = Camera.mainCamera.ScreenPointToRay(Input.mousePosition);

//Casta a raycast all the time, so after i will make a check to see what the player had shooted
Physics.Raycast(ray, hit, Mathf.Infinity);

//when shoot...
if(Input.GetButtonDown("Fire1")){
var instance : GameObject = Instantiate(bullet, bulletSpawnPoint.transform.position, Quaternion.identity);
Physics.IgnoreCollision(instance.collider, bulletSpawnPoint.collider);

//HOW CAN I MAKE THE PROJECTILE GOES INTO THE MOUSE POSITION?!
instance.rigidbody.useGravity = false;
instance.transform.LookAt(hit.point);
instance.rigidbody.velocity = instance.transform.forward * 10;

//Destroy the projectile
Destroy(instance, 4);

//Debug
clicks++;
Debug.Log("Voce acertou um: " + hit.transform.name.ToString() + " com " + clicks + " balas ate agora...");

}
}

EDIT 1: Here is my new code, a got what a want.
What do you think about it? Is it good?

function Shoot(){

ray = Camera.mainCamera.ScreenPointToRay(Input.mousePosition);

if(Physics.Raycast(ray, hit, Mathf.Infinity)){
//Debug.Log("Voce esta acertando um: " + hit.transform.name.ToString());

if(Input.GetButtonDown("Fire1")){
var instance : GameObject = Instantiate(bullet, bulletSpawnPoint.transform.position, Quaternion.identity);
Physics.IgnoreCollision(instance.collider, bulletSpawnPoint.collider);

//Instancia o projectil e ascelera-o para a direção do mouse
instance.rigidbody.useGravity = false;
instance.transform.LookAt(hit.point);
instance.rigidbody.velocity = instance.transform.forward * bulletSpeed;

//DestroI o projetil
Destroy(instance, bulletLifeTime);

Debug.Log("Acertou " + hit.collider.gameObject.tag);

//if(hit.collider.gameObject.tag == "Enemy"){
// Debug.Log("Acertou " + hit.collider.gameObject.tag);
//}
}
}
}