That improvement has been made possible by (a) increases in recording density (the amount of data squeezed on a disk platter) that translate into corresponding increases in transfer performance; (b) increased performance of the SATA interface, now 3 Gb/s; and (c) faster 7200 RPM drives that increase transfer performance and reduce latency (delays) over slower rotation drives.
Each generation is faster than the last. It's important to get the latest generation, and since each generation is offered in a variety of capacities, it can be hard to figure out which generation is which. 160 GB 7200 RPM, for example, is available from Hitachi Global Storage Technologies in 3rd (Travelstar 7K200), 4th (Travelstar 7K320), and 5th (Travelstar 7K500) generation versions, identified only by model number.
In addition to generation, similar drives from different manufacturers have significant differences in performance due to differences in technology, including architecture and on-board control firmware. Different brands are not the same!
- Hitachi Travelstar 7K500 - Hitachi took the time to get it right, and the result is a superb product with blazing performance, smooth and quiet operation, and high reliability. Encrypting and high availability versions are also offered. Find It Online with Google Products
- Western Digital Scorpio Black - Very good, but only 4th generation. Find It Online with Google Products
- Western Digital Scorpio Blue - Only 5200 RPM, but higher capacities than 7200 RPM, and very good performance due to excellent architecture and on-board control firmware. Find It Online with Google Products