A new technology should dramatically increase the density of hard drives, Western Digital claims. The company says it has developed a combination of perpendicular magnetic recording and tunneling magneto-resistive heads to push density to 520GB per square inch, an amount even higher than that recently announced by Hitachi, and far beyond most common drives; Western notes that its 250GB Scorpio model has 200GB per square inch. The company expects to eventually put 640GB on a single platter by 2010, and release a 3.5-inch, 3TB drive the same year, beating Hitachi's anticipated 4TB unit to market.