If you can't beat SSDs (and you can't, we've checked), you might as well try and dress like them by squeezing into the unreasonably low profile of just 7mm. Such must be the reasoning behind Hitachi's svelte 7mm-thick HDD series, which today gets augmented with a new top-of-the-line drive boasting 500GB of storage room. This single-platter archivist measure 2.5 inches diagonally, but as its Z5K500 product name suggests, it only spins at the tame rate of 5400RPM. The less generously proportioned Z7K320 offers 7200RPM
