The result is a Mac OS X update unlike any in recent memory, one that boosts speeds, reclaims disk space, tweaks dozens of features, and lays the groundwork for a new generation of computers that feature 64-bit multicore microprocessors, ultra-powerful graphics processors, and massive amounts of memory. These features, combined with the low upgrade price of £25, make Snow Leopard the biggest no-brainer of an upgrade since Mac OS X 10.1. (And that upgrade, the aged among us will recall, was completely free.)

Making the upgrade

Unlike previous editions of Mac OS X, which could be freely installed on any old Mac, Snow Leopard's license specifically limits it to users who are already using Leopard, which has been shipping since October 2007. If you are a Leopard user, you can upgrade a single Mac for £25, or up to five Macs in one household with the Snow Leopard Family Pack for £39. Users of Tiger - essentially people who bought Intel Macs before Leopard was released and never upgraded - are supposed to purchase the Mac Box Set, which includes Snow Leopard, iLife '09, and iWork '09, for £129. (Snow Leopard doesn't run at all on PowerPC-based Macs.)

However, in contrast to Microsoft - which offers a confusing array of full and upgrade versions of Windows, all of them requiring that users enter a unique serial number in order to prove they're not pirates - Apple continues to rely on the honor system for Mac OS X. Not only does Snow Leopard not require the entry of any serial numbers, but the standard version of Snow Leopard is a bootable "full install" disc that doesn't actually check for the presence of Leopard in order to install. This also means that if, at a later time, you want to wipe your hard drive and reinstall Snow Leopard, you won't have to first install Leopard and then run a separate Snow Leopard upgrade on top of it. (That sound you hear is a thousand IT managers sighing with relief.)

The Snow Leopard installation process is somewhat different from previous OS X installers. Rather than requiring an immediate restart, a lot of it takes place as soon as you double-click the installer. In essence, Apple has taken the wait out of the process: Now you set up all your installation settings and walk away; the rest of the process (including a reboot) can take place without your direct intervention. And the installation process itself takes less time in Snow Leopard than it did in Leopard.