Apple It was in 2001 that Apple and Microsoft unveiled their respective new pride-and-joys - each had shiny new operating systems. In the one corner was Mac OS X 10.0, an amalgamation of FreeBSD Unix and the classic Mac OS; in the other corner, Windows XP, a reskinned version of Windows 2000, itself based on Microsoft Windows NT.

In the intervening years, we've seen Win XP soldier on with three Service Packs to patch the code, punctuated by Microsoft's fanfare of Windows Vista in 2006 as the great XP replacement. It didn't take long for the world to turn its collective nose up at a system that was slower and even more cumbersome than what had gone before.

Meanwhile Apple has made six nearly yearly ‘point' updates, up to the OS X 10.6 released worldwide today. The underlying system has been tweaked and optimised, while new user interface features have been trickled in to make life easier getting around the system. Not to mention the debut of the kind of UI tricks that detractors have dismissed as pure eye candy, such as juggling open application windows with Exposé's shuffling show.

In marked contrast to Windows, OS X has sped up with each new update - and today's Snow Leopard sees some of the most conspicuous oiling of the internal wheels yet.

Granted, the original 10.0 version of OS X, then 10.1, and probably even a few ‘points' after that, were somewhat slooow in the user interface department. Resizing windows, for instance, you'd feel the UI latency, a lag between what your cursor was doing and what would happen on-screen. Mac users would eagerly await the next update. ‘Is it snappier?' was the first question on everyone's lips after hearing of a new incremental update.

By the time we hit 10.5 Tiger, things had settled down in the speed department, helped along by the transition to Intel processors halfway through that OS's lifespan in 2006. Going Intel, no longer was a dual-core CPU the preserve of hulking Mac G5 towers. Even MacBook laptops would enjoy the extra grunt that a second processor core could bring to the Mac OS X operating system.

So now we have an OS entirely stripped of the PPC code used by G4 and G5 Macs. And 64-bit computing is being heralded with even more trumpets this time around, even if Snow Leopard is actually a clever fusion of 32-bit and 64-bit processing; by default, most Macs will still load a 32-bit kernel unless you play with the ‘6' and ‘4' keys at startup.

But the proof of this pudding is in the playing - and boy, does Snow Leopard feel Snappy! This is predominantly down to the new Finder, the primary interface point for gadding about a Mac.

Windows zip around the screen with more élan, interface animations are smoother and more natural - in fact, activating Exposé on my MacBook Pro is almost too quick. The jump from overlapping windows to a lightbox-like overview is so fast, you miss the organic transition from one viewpoint to the next.

To get a quick idea of what some code tidying had done, I looked at the processor load on the all-new QuickTime player app.

Using a 2-minute high-definition clip (H.264, 1920x800), I found that QT7 in Leopard would take 71% of both CPUs' combined power, when averaged over the entire video.

In Snow Leopard, the same extract played through QuickTime X used an average of 52% of horsepower (where ‘maximum' in both examples would of course be 200% in a dual-core laptop).

But I already miss what's been stripped out of QuickTime X. Fixing aspect ratios and exporting to a wide range of codecs, for example, are key QuickTime Pro features not available until Apple releases a QuickTime Pro version of QT X.

Thankfully, all those Pro features are still available by opting in for QuickTime 7 from the Snow Leopard installer disc. That will have to do until QT X Pro appears.

Snow in August

Apple's release of Snow Leopard before its advertised September launch date could be significant. Apple knows that Windows Vista 6.1, aka Windows 7, will win back Vista holdouts.

Both Snow Leopard and Windows 7 are refinements of their immediate predecessors - although it was Vista 6.0 that was the one in real dire need of fixing.

And not only has Apple launched early to give more time for the back-to-school buyers to mull over their computing choices, for example, but it's made its upgrade irresistibly affordable.

While Microsoft ties itself in knots with multiple versions at different prices and with different time-limited special offers depending on whether you're buying full or upgrade, single or three-seat family, Apple has kept it simple: 25 quid. Or £39 if you have several Macs to upgrade and you want to abide by the license agreement.

For unlike the royal pain that is called installing Microsoft Windows, Mac OS X requires no serial code. It has no online activation system. No incessant nags to activate. And no ‘you are stealing our software'-type messages with funereal black wallpaper if you dare not to connect to the company's servers inside 30 days.

Moreover, while Windows 7 ranges in price from about £65 to £230 or more, depending on which offer is flagged that day and whether there's an R in the month, Snow Leopard will install on any Intel Mac for £25.

Which is quite a good deal for the more polished operating system, one that lets you enjoy your computer without sending you neurotic about viruses or treat you like a criminal when you're late with your online activation.