it dosnt relly make a difirence at all what capacity or rotation per minut to buy its all up to ur taste, this litle baby can take anything u throw at it but if u have the money to spend i sugjest u get an ssd drive (solid state drive) they are very expensive at the moment and the majority are 320gb max the latest gen has got more capacity of 500gb and over but they cost twice AS MUch as ur box they run faster no rotation and cooler there is no motor that gets over hot its basicaly a big peace of ram mamory.