Becoming one of the few to cross the 500GB milestone, Toshiba late on Tuesday added a 640GB drive to its notebook-sized GSX hard drives. With two platters to make up its entire storage, the 5,400RPM disk is thin enough at 9.5mm tall to fit in thin-and-light notebooks and also gets incidental boosts from the increased density. Toshiba claims that it's faster, with "significant" speed-ups through
