The rivalry between major laptop hard drive makers continues to heat up. Last week, Hitachi beat Samsung to the punch by announcing the world’s first 500GB hard drive, which added a third platter and a few millimeters thickness to achieve the boost in capacity.

But Samsung one-upped Hitachi today by unveiling its new Spinpoint M6 500GB, the first 500 GB 2.5’’ hard drive that actually fits in the industry’s standard 9.5mm height dimension, meaning current mainstream notebook PCs can now support capacities of up to one terabyte by installing two of these massive drives. The Spinpoint M6 500GB hard drive features a 5400rpm spindle speed, a 8MB cache, 3.0Gbps SATA interface, and is expected to be available in March 2008.