Just replaced by WD500GB Blue to the Samsung 640GB hard drive. $99 at Newegg with $1 delivery. It is the 2 platter design with 9.5 mm height. Given the super high density of each platter, the performance is expected to be somewhat higher.... Installed it last night after SuperDuper copy. It is clearly much snappier than the WD model I had. The bouncing balls seems to have decreased at launch by at least 30-50%. Another thing, it is super quiet. I cannot hear it at all!! No head seek/park click sounds I had with the Blue. Highly recommended.