According Microsoft head honcho Steve Ballmer, by the end of 2007 there will be more WIndows computers than there are cars in the world. The company says it sold 40 million copies of Windows Vista in the first 100 days after it launched earlier this year.

And the biggest single reason people upgrade, at least as far as Microsoft's market research tells it?

Security concerns, which is something we can sympathise with - and despite all the concerns over Digital Rights Management and privacy in the new operating system, Vista's security features certainly improve upon those in XP.