Toshiba just bested its own 320GB hard drive with a 400GB offering in the same 9.5-mm height form factor favored by most thin laptops. That's as good as it gets unless you can track down Sammy's elusive 500GB Spinpoint M6. The MK4058GSX spins just 2 platters which means the disk sports an impressive 477Mbit/mm2 (308Gbpsi) areal density while consuming 20% less power (0.0015W/GB energy consumption efficiency) and 2dB less noise than its own 320GB predecessor. Rounding out the specs are a 12-ms average seek and 8MB cache. Toshiba also boosted the rest of its 9.5-mm, 2.5-inch, 3.0Gbps SATA disk lineup to 7,200rpm including the 320GB MK3254GSY. Mass production of the 400GB slab is expected to begin in September while the 7,200 HDDs will hit the market in August. No prices announced.