HOW CAN I TURN OFF MY MOUSEPAD?

i have just attached an optic mouse on my laptop a Fujitsu amilo L7320GW. PROBLEM IS NOW WHEN I TYPE ON THE LAPTOP SOMETIMES THE KEYS DO NOT WORK AND I THINK I AM TOUCHING MY MOUSEPAD SO THE CURSOR MOVES ALL OVER THE PLACE THE POINTER MOVES ON ITS OWN AND OPENS WINDOWS ON ITS OWN! I NEED TO TURN OFF MY MOUSEPAD ON THE LAPTOP BECAUSE THEY ARE BOTH WORKING BUT I DO NOT KNOW HOW TO DO IT ANYONE KNOW.