Mac OS X Mavericks: £0

Apple is so keen for you to upgrade to its new version of OSX, it’s made it a free download.

Apple has never charged much for its class-leading desktop operating system – last year Mountain Lion was yours for £14, and in 2011 Lion went for a non-princely £21 – but the latest update is available for exactly no pounds. 

That absence of money buys you improved battery life and better graphics on the same computer, adding up to an hour of extra web browsing on the latest MacBook Air. It also adds a bundle of new apps for Maps, iBooks, Safari and many more, and herein lies the reason for Apple’s free OS: if more people upgrade to it, more people use Mac apps instead of websites (websites like, oh, Google Maps), Mac apps become as popular as iOS apps and… ker-ching!

Moments before announcing this at Apple’s event this evening, Senior Vice President Craig Federighi showed a nice big slide of the Windows 8.1 box, complete with its US$199 pricetag (£189 in the UK, or £99 for regular Windows 8). Then he chuckled, the sort of rich, contented sound someone makes when they win a game of cards or get a surprise tax rebate. 

Other free desktop operating systems include Linux and, er, Linux.