Apple Mac OS X Version 10.5.1 Leopard (DVD-ROM) Retail Version 10.5.1 Model Number MB427Z/A Introduces over 300 new and enhanced features to OS X. Including a new desktop and updated finder enabling easy browsing and sharing between multiple Macs Preview files without opening an application using Quick Look Take advantage of the latest developments in processor hardware with full native 64-bit support, multi-core optimization, and new Core animation