"The storage system maker announced a $240 320GB external hard drive, joining a 250GB drive the company introduced in June. Both drives also can link with USB 2.0, which transfers data three times more slowly. SATA (Serial AT Attachment) technology connects hard drives inside computers; eSATA (external SATA) uses a connector on the outside of the computer chassis so drives can be connected externally. Iomega and rivals such as Seagate started selling eSATA drives this year."The speed difference will be very attractive to those with large amounts of data to process. However, since it does not have the ubiquity of USB 2.0 and is priced higher than other external drives, I don't see market penetration beyond that.