In Snow Leopard, Apple focused on making the OS run faster using technologies like Grand Central Dispatch (which allows a Mac with a multi-core processor to more effectively distribute work among cores) and OpenCL (which allows a Mac's graphics processors to be used for general computing tasks whenever possible), and making all the core system applications and most core components 64-bit.
But before you can appreciate Snow Leopard's performance, user interface refinements, and technology tweaks, you have to get it installed. Here's what you need to know about the upgrade process - which in itself illustrates both UI improvements and under-the-hood advances over past versions of Mac OS X.
Can you run Snow Leopard?
The most important question to answer before upgrading to Snow Leopard is whether your Mac can handle it. First, you'll need an Intel-based Mac. (Not sure what you have? Click the Apple menu and choose About This Mac. If your processor is a PowerPC, you're out of luck; if it's from Intel, you're good to go.)
Any Intel Mac will run Snow Leopard, provided it has at least 1GB of RAM (though 2GB or more will deliver better performance) and 5GB of hard drive space. You'll also need a DVD drive for installation. (MacBook Air owners can use a DVD drive in another computer, provided they turn on CD/DVD sharing.)
It's worth noting that not all Intel Macs can make use of 64-bit processing. That's because not all Intel Macs have 64-bit processors.
The first Intel Macs shipped with either an Intel Core Duo or Core Solo chip, both of them 32-bit processors. Apple switched to the Core 2 Duo processor, which is 64-bit, across most of its product lines pretty quickly. You can check your processor model using About This Mac.
With an Intel Core 2 Duo processor and 2GB of RAM, this iMac - still running Mac OS X 10.4 "Tiger" - can take advantage of Snow Leopard's 64-bit processing.
This doesn't mean that early Intel Macs won't see improvements with Snow Leopard - they will - but they may not see as big a performance boost as newer Macs.
Any Mac users still running Tiger (Mac OS X 10.4) can upgrade directly to Snow Leopard, skipping its predecessor, by purchasing Apple's Mac Box Set, which includes Snow Leopard and the latest versions of iLife and iWork for £129. This ensures that your Mac will be able to run all the Apple tools as well as Snow Leopard.
Important: Before you upgrade, back up
Before you even think about installing the new operating system, be sure to perform a full backup of your system.
With Snow Leopard, Apple has made the installation process cleaner and more reliable than ever; the installer can even finish an installation properly if your Mac is unexpectedly powered off during the process. Nevertheless, a good backup is always prudent. If you've been using Time Machine in Leopard, you've probably got one already.