Other World Computing (OWC) on Thursday offered its first 100GB Mercury On-the-Go Portable 2.5-inch external hard disk drive. Available for US$319.97, the drive features a 5400RPM mechanism with 8MB of cache. It comes in either FireWire-only or FireWire and USB 2.0 interfaces. The drive weighs 11 ounces and measures 3.5 x 5.5 x 1.0 inches. It’s compatible with Mac OS X, 8.6 or higher and various versions of Windows.