Mac OS X Snow Leopard.Available August 28.Upgrade from Leopard for just $29

Refined, not reinvented.
Mac OS X is renowned for its simplicity, its reliability, and its ease of use. So when it came to designing Snow Leopard, Apple engineers had a single goal: to make a great thing even better. They searched for areas to refine, further simplify, and speed up — from little things like ejecting external drives to big things like installing the OS. In many cases, they elevated great to amazing. Here are just a few examples of how your Mac experience was fine-tuned.
64-bit support
64-bit computing used to be the province of scientists and engineers, but now this generational shift in computing gives all users the tools to apply the power of 64-bit to speed up everything from everyday applications to the most demanding scientific computations. Although Mac OS X is already 64-bit capable in many ways, Snow Leopard takes the next big step by rewriting nearly all system applications in 64-bit code¹ and by enabling the Mac to address massive amounts of memory. Now Mac OS X is faster, more secure, and completely ready for the future.
Grand Central dispatch
More cores, not faster clock speeds, drive performance increases in today’s processors. Grand Central Dispatch takes full advantage by making all of Mac OS X multicore aware and optimizing it for allocating tasks across multiple cores and processors. Grand Central Dispatch also makes it much easier for developers to create programs that squeeze every last drop of power from multicore systems.
OpenCL
With graphics processors surpassing speeds of a trillion operations per second, they’re capable of considerably more than just drawing pictures. OpenCL in Snow Leopard is a technology that makes it possible for developers to tap the vast gigaflops of computing power currently in the graphics processor and use it for any application.
QuickTime X
Snow Leopard introduces QuickTime X, a major leap forward that advances modern media and Internet standards. QuickTime X includes a brand-new player application, offers optimized support for modern codecs, and delivers more efficient media playback, making it ideal for any application that needs to play media content.
Out of the box supprt for Microsoft Exchange Server
With Snow Leopard, the Mac is the only computer with built-in support for the latest version of Microsoft Exchange Server. So you can use your Mac — with all the features and applications you love — at home and at work and have all your messages, meetings, and contacts in one place.